linux/drivers/video/udlfb.c
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   1/*
   2 * udlfb.c -- Framebuffer driver for DisplayLink USB controller
   3 *
   4 * Copyright (C) 2009 Roberto De Ioris <roberto@unbit.it>
   5 * Copyright (C) 2009 Jaya Kumar <jayakumar.lkml@gmail.com>
   6 * Copyright (C) 2009 Bernie Thompson <bernie@plugable.com>
   7 *
   8 * This file is subject to the terms and conditions of the GNU General Public
   9 * License v2. See the file COPYING in the main directory of this archive for
  10 * more details.
  11 *
  12 * Layout is based on skeletonfb by James Simmons and Geert Uytterhoeven,
  13 * usb-skeleton by GregKH.
  14 *
  15 * Device-specific portions based on information from Displaylink, with work
  16 * from Florian Echtler, Henrik Bjerregaard Pedersen, and others.
  17 */
  18
  19#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  20
  21#include <linux/module.h>
  22#include <linux/kernel.h>
  23#include <linux/init.h>
  24#include <linux/usb.h>
  25#include <linux/uaccess.h>
  26#include <linux/mm.h>
  27#include <linux/fb.h>
  28#include <linux/vmalloc.h>
  29#include <linux/slab.h>
  30#include <linux/prefetch.h>
  31#include <linux/delay.h>
  32#include <video/udlfb.h>
  33#include "edid.h"
  34
  35static struct fb_fix_screeninfo dlfb_fix = {
  36        .id =           "udlfb",
  37        .type =         FB_TYPE_PACKED_PIXELS,
  38        .visual =       FB_VISUAL_TRUECOLOR,
  39        .xpanstep =     0,
  40        .ypanstep =     0,
  41        .ywrapstep =    0,
  42        .accel =        FB_ACCEL_NONE,
  43};
  44
  45static const u32 udlfb_info_flags = FBINFO_DEFAULT | FBINFO_READS_FAST |
  46                FBINFO_VIRTFB |
  47                FBINFO_HWACCEL_IMAGEBLIT | FBINFO_HWACCEL_FILLRECT |
  48                FBINFO_HWACCEL_COPYAREA | FBINFO_MISC_ALWAYS_SETPAR;
  49
  50/*
  51 * There are many DisplayLink-based graphics products, all with unique PIDs.
  52 * So we match on DisplayLink's VID + Vendor-Defined Interface Class (0xff)
  53 * We also require a match on SubClass (0x00) and Protocol (0x00),
  54 * which is compatible with all known USB 2.0 era graphics chips and firmware,
  55 * but allows DisplayLink to increment those for any future incompatible chips
  56 */
  57static struct usb_device_id id_table[] = {
  58        {.idVendor = 0x17e9,
  59         .bInterfaceClass = 0xff,
  60         .bInterfaceSubClass = 0x00,
  61         .bInterfaceProtocol = 0x00,
  62         .match_flags = USB_DEVICE_ID_MATCH_VENDOR |
  63                USB_DEVICE_ID_MATCH_INT_CLASS |
  64                USB_DEVICE_ID_MATCH_INT_SUBCLASS |
  65                USB_DEVICE_ID_MATCH_INT_PROTOCOL,
  66        },
  67        {},
  68};
  69MODULE_DEVICE_TABLE(usb, id_table);
  70
  71/* module options */
  72static bool console = 1; /* Allow fbcon to open framebuffer */
  73static bool fb_defio = 1;  /* Detect mmap writes using page faults */
  74static bool shadow = 1; /* Optionally disable shadow framebuffer */
  75static int pixel_limit; /* Optionally force a pixel resolution limit */
  76
  77/* dlfb keeps a list of urbs for efficient bulk transfers */
  78static void dlfb_urb_completion(struct urb *urb);
  79static struct urb *dlfb_get_urb(struct dlfb_data *dev);
  80static int dlfb_submit_urb(struct dlfb_data *dev, struct urb * urb, size_t len);
  81static int dlfb_alloc_urb_list(struct dlfb_data *dev, int count, size_t size);
  82static void dlfb_free_urb_list(struct dlfb_data *dev);
  83
  84/*
  85 * All DisplayLink bulk operations start with 0xAF, followed by specific code
  86 * All operations are written to buffers which then later get sent to device
  87 */
  88static char *dlfb_set_register(char *buf, u8 reg, u8 val)
  89{
  90        *buf++ = 0xAF;
  91        *buf++ = 0x20;
  92        *buf++ = reg;
  93        *buf++ = val;
  94        return buf;
  95}
  96
  97static char *dlfb_vidreg_lock(char *buf)
  98{
  99        return dlfb_set_register(buf, 0xFF, 0x00);
 100}
 101
 102static char *dlfb_vidreg_unlock(char *buf)
 103{
 104        return dlfb_set_register(buf, 0xFF, 0xFF);
 105}
 106
 107/*
 108 * Map FB_BLANK_* to DisplayLink register
 109 * DLReg FB_BLANK_*
 110 * ----- -----------------------------
 111 *  0x00 FB_BLANK_UNBLANK (0)
 112 *  0x01 FB_BLANK (1)
 113 *  0x03 FB_BLANK_VSYNC_SUSPEND (2)
 114 *  0x05 FB_BLANK_HSYNC_SUSPEND (3)
 115 *  0x07 FB_BLANK_POWERDOWN (4) Note: requires modeset to come back
 116 */
 117static char *dlfb_blanking(char *buf, int fb_blank)
 118{
 119        u8 reg;
 120
 121        switch (fb_blank) {
 122        case FB_BLANK_POWERDOWN:
 123                reg = 0x07;
 124                break;
 125        case FB_BLANK_HSYNC_SUSPEND:
 126                reg = 0x05;
 127                break;
 128        case FB_BLANK_VSYNC_SUSPEND:
 129                reg = 0x03;
 130                break;
 131        case FB_BLANK_NORMAL:
 132                reg = 0x01;
 133                break;
 134        default:
 135                reg = 0x00;
 136        }
 137
 138        buf = dlfb_set_register(buf, 0x1F, reg);
 139
 140        return buf;
 141}
 142
 143static char *dlfb_set_color_depth(char *buf, u8 selection)
 144{
 145        return dlfb_set_register(buf, 0x00, selection);
 146}
 147
 148static char *dlfb_set_base16bpp(char *wrptr, u32 base)
 149{
 150        /* the base pointer is 16 bits wide, 0x20 is hi byte. */
 151        wrptr = dlfb_set_register(wrptr, 0x20, base >> 16);
 152        wrptr = dlfb_set_register(wrptr, 0x21, base >> 8);
 153        return dlfb_set_register(wrptr, 0x22, base);
 154}
 155
 156/*
 157 * DisplayLink HW has separate 16bpp and 8bpp framebuffers.
 158 * In 24bpp modes, the low 323 RGB bits go in the 8bpp framebuffer
 159 */
 160static char *dlfb_set_base8bpp(char *wrptr, u32 base)
 161{
 162        wrptr = dlfb_set_register(wrptr, 0x26, base >> 16);
 163        wrptr = dlfb_set_register(wrptr, 0x27, base >> 8);
 164        return dlfb_set_register(wrptr, 0x28, base);
 165}
 166
 167static char *dlfb_set_register_16(char *wrptr, u8 reg, u16 value)
 168{
 169        wrptr = dlfb_set_register(wrptr, reg, value >> 8);
 170        return dlfb_set_register(wrptr, reg+1, value);
 171}
 172
 173/*
 174 * This is kind of weird because the controller takes some
 175 * register values in a different byte order than other registers.
 176 */
 177static char *dlfb_set_register_16be(char *wrptr, u8 reg, u16 value)
 178{
 179        wrptr = dlfb_set_register(wrptr, reg, value);
 180        return dlfb_set_register(wrptr, reg+1, value >> 8);
 181}
 182
 183/*
 184 * LFSR is linear feedback shift register. The reason we have this is
 185 * because the display controller needs to minimize the clock depth of
 186 * various counters used in the display path. So this code reverses the
 187 * provided value into the lfsr16 value by counting backwards to get
 188 * the value that needs to be set in the hardware comparator to get the
 189 * same actual count. This makes sense once you read above a couple of
 190 * times and think about it from a hardware perspective.
 191 */
 192static u16 dlfb_lfsr16(u16 actual_count)
 193{
 194        u32 lv = 0xFFFF; /* This is the lfsr value that the hw starts with */
 195
 196        while (actual_count--) {
 197                lv =     ((lv << 1) |
 198                        (((lv >> 15) ^ (lv >> 4) ^ (lv >> 2) ^ (lv >> 1)) & 1))
 199                        & 0xFFFF;
 200        }
 201
 202        return (u16) lv;
 203}
 204
 205/*
 206 * This does LFSR conversion on the value that is to be written.
 207 * See LFSR explanation above for more detail.
 208 */
 209static char *dlfb_set_register_lfsr16(char *wrptr, u8 reg, u16 value)
 210{
 211        return dlfb_set_register_16(wrptr, reg, dlfb_lfsr16(value));
 212}
 213
 214/*
 215 * This takes a standard fbdev screeninfo struct and all of its monitor mode
 216 * details and converts them into the DisplayLink equivalent register commands.
 217 */
 218static char *dlfb_set_vid_cmds(char *wrptr, struct fb_var_screeninfo *var)
 219{
 220        u16 xds, yds;
 221        u16 xde, yde;
 222        u16 yec;
 223
 224        /* x display start */
 225        xds = var->left_margin + var->hsync_len;
 226        wrptr = dlfb_set_register_lfsr16(wrptr, 0x01, xds);
 227        /* x display end */
 228        xde = xds + var->xres;
 229        wrptr = dlfb_set_register_lfsr16(wrptr, 0x03, xde);
 230
 231        /* y display start */
 232        yds = var->upper_margin + var->vsync_len;
 233        wrptr = dlfb_set_register_lfsr16(wrptr, 0x05, yds);
 234        /* y display end */
 235        yde = yds + var->yres;
 236        wrptr = dlfb_set_register_lfsr16(wrptr, 0x07, yde);
 237
 238        /* x end count is active + blanking - 1 */
 239        wrptr = dlfb_set_register_lfsr16(wrptr, 0x09,
 240                        xde + var->right_margin - 1);
 241
 242        /* libdlo hardcodes hsync start to 1 */
 243        wrptr = dlfb_set_register_lfsr16(wrptr, 0x0B, 1);
 244
 245        /* hsync end is width of sync pulse + 1 */
 246        wrptr = dlfb_set_register_lfsr16(wrptr, 0x0D, var->hsync_len + 1);
 247
 248        /* hpixels is active pixels */
 249        wrptr = dlfb_set_register_16(wrptr, 0x0F, var->xres);
 250
 251        /* yendcount is vertical active + vertical blanking */
 252        yec = var->yres + var->upper_margin + var->lower_margin +
 253                        var->vsync_len;
 254        wrptr = dlfb_set_register_lfsr16(wrptr, 0x11, yec);
 255
 256        /* libdlo hardcodes vsync start to 0 */
 257        wrptr = dlfb_set_register_lfsr16(wrptr, 0x13, 0);
 258
 259        /* vsync end is width of vsync pulse */
 260        wrptr = dlfb_set_register_lfsr16(wrptr, 0x15, var->vsync_len);
 261
 262        /* vpixels is active pixels */
 263        wrptr = dlfb_set_register_16(wrptr, 0x17, var->yres);
 264
 265        /* convert picoseconds to 5kHz multiple for pclk5k = x * 1E12/5k */
 266        wrptr = dlfb_set_register_16be(wrptr, 0x1B,
 267                        200*1000*1000/var->pixclock);
 268
 269        return wrptr;
 270}
 271
 272/*
 273 * This takes a standard fbdev screeninfo struct that was fetched or prepared
 274 * and then generates the appropriate command sequence that then drives the
 275 * display controller.
 276 */
 277static int dlfb_set_video_mode(struct dlfb_data *dev,
 278                                struct fb_var_screeninfo *var)
 279{
 280        char *buf;
 281        char *wrptr;
 282        int retval = 0;
 283        int writesize;
 284        struct urb *urb;
 285
 286        if (!atomic_read(&dev->usb_active))
 287                return -EPERM;
 288
 289        urb = dlfb_get_urb(dev);
 290        if (!urb)
 291                return -ENOMEM;
 292
 293        buf = (char *) urb->transfer_buffer;
 294
 295        /*
 296        * This first section has to do with setting the base address on the
 297        * controller * associated with the display. There are 2 base
 298        * pointers, currently, we only * use the 16 bpp segment.
 299        */
 300        wrptr = dlfb_vidreg_lock(buf);
 301        wrptr = dlfb_set_color_depth(wrptr, 0x00);
 302        /* set base for 16bpp segment to 0 */
 303        wrptr = dlfb_set_base16bpp(wrptr, 0);
 304        /* set base for 8bpp segment to end of fb */
 305        wrptr = dlfb_set_base8bpp(wrptr, dev->info->fix.smem_len);
 306
 307        wrptr = dlfb_set_vid_cmds(wrptr, var);
 308        wrptr = dlfb_blanking(wrptr, FB_BLANK_UNBLANK);
 309        wrptr = dlfb_vidreg_unlock(wrptr);
 310
 311        writesize = wrptr - buf;
 312
 313        retval = dlfb_submit_urb(dev, urb, writesize);
 314
 315        dev->blank_mode = FB_BLANK_UNBLANK;
 316
 317        return retval;
 318}
 319
 320static int dlfb_ops_mmap(struct fb_info *info, struct vm_area_struct *vma)
 321{
 322        unsigned long start = vma->vm_start;
 323        unsigned long size = vma->vm_end - vma->vm_start;
 324        unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
 325        unsigned long page, pos;
 326
 327        if (offset + size > info->fix.smem_len)
 328                return -EINVAL;
 329
 330        pos = (unsigned long)info->fix.smem_start + offset;
 331
 332        pr_notice("mmap() framebuffer addr:%lu size:%lu\n",
 333                  pos, size);
 334
 335        while (size > 0) {
 336                page = vmalloc_to_pfn((void *)pos);
 337                if (remap_pfn_range(vma, start, page, PAGE_SIZE, PAGE_SHARED))
 338                        return -EAGAIN;
 339
 340                start += PAGE_SIZE;
 341                pos += PAGE_SIZE;
 342                if (size > PAGE_SIZE)
 343                        size -= PAGE_SIZE;
 344                else
 345                        size = 0;
 346        }
 347
 348        return 0;
 349}
 350
 351/*
 352 * Trims identical data from front and back of line
 353 * Sets new front buffer address and width
 354 * And returns byte count of identical pixels
 355 * Assumes CPU natural alignment (unsigned long)
 356 * for back and front buffer ptrs and width
 357 */
 358static int dlfb_trim_hline(const u8 *bback, const u8 **bfront, int *width_bytes)
 359{
 360        int j, k;
 361        const unsigned long *back = (const unsigned long *) bback;
 362        const unsigned long *front = (const unsigned long *) *bfront;
 363        const int width = *width_bytes / sizeof(unsigned long);
 364        int identical = width;
 365        int start = width;
 366        int end = width;
 367
 368        prefetch((void *) front);
 369        prefetch((void *) back);
 370
 371        for (j = 0; j < width; j++) {
 372                if (back[j] != front[j]) {
 373                        start = j;
 374                        break;
 375                }
 376        }
 377
 378        for (k = width - 1; k > j; k--) {
 379                if (back[k] != front[k]) {
 380                        end = k+1;
 381                        break;
 382                }
 383        }
 384
 385        identical = start + (width - end);
 386        *bfront = (u8 *) &front[start];
 387        *width_bytes = (end - start) * sizeof(unsigned long);
 388
 389        return identical * sizeof(unsigned long);
 390}
 391
 392/*
 393 * Render a command stream for an encoded horizontal line segment of pixels.
 394 *
 395 * A command buffer holds several commands.
 396 * It always begins with a fresh command header
 397 * (the protocol doesn't require this, but we enforce it to allow
 398 * multiple buffers to be potentially encoded and sent in parallel).
 399 * A single command encodes one contiguous horizontal line of pixels
 400 *
 401 * The function relies on the client to do all allocation, so that
 402 * rendering can be done directly to output buffers (e.g. USB URBs).
 403 * The function fills the supplied command buffer, providing information
 404 * on where it left off, so the client may call in again with additional
 405 * buffers if the line will take several buffers to complete.
 406 *
 407 * A single command can transmit a maximum of 256 pixels,
 408 * regardless of the compression ratio (protocol design limit).
 409 * To the hardware, 0 for a size byte means 256
 410 *
 411 * Rather than 256 pixel commands which are either rl or raw encoded,
 412 * the rlx command simply assumes alternating raw and rl spans within one cmd.
 413 * This has a slightly larger header overhead, but produces more even results.
 414 * It also processes all data (read and write) in a single pass.
 415 * Performance benchmarks of common cases show it having just slightly better
 416 * compression than 256 pixel raw or rle commands, with similar CPU consumpion.
 417 * But for very rl friendly data, will compress not quite as well.
 418 */
 419static void dlfb_compress_hline(
 420        const uint16_t **pixel_start_ptr,
 421        const uint16_t *const pixel_end,
 422        uint32_t *device_address_ptr,
 423        uint8_t **command_buffer_ptr,
 424        const uint8_t *const cmd_buffer_end)
 425{
 426        const uint16_t *pixel = *pixel_start_ptr;
 427        uint32_t dev_addr  = *device_address_ptr;
 428        uint8_t *cmd = *command_buffer_ptr;
 429        const int bpp = 2;
 430
 431        while ((pixel_end > pixel) &&
 432               (cmd_buffer_end - MIN_RLX_CMD_BYTES > cmd)) {
 433                uint8_t *raw_pixels_count_byte = 0;
 434                uint8_t *cmd_pixels_count_byte = 0;
 435                const uint16_t *raw_pixel_start = 0;
 436                const uint16_t *cmd_pixel_start, *cmd_pixel_end = 0;
 437
 438                prefetchw((void *) cmd); /* pull in one cache line at least */
 439
 440                *cmd++ = 0xAF;
 441                *cmd++ = 0x6B;
 442                *cmd++ = (uint8_t) ((dev_addr >> 16) & 0xFF);
 443                *cmd++ = (uint8_t) ((dev_addr >> 8) & 0xFF);
 444                *cmd++ = (uint8_t) ((dev_addr) & 0xFF);
 445
 446                cmd_pixels_count_byte = cmd++; /*  we'll know this later */
 447                cmd_pixel_start = pixel;
 448
 449                raw_pixels_count_byte = cmd++; /*  we'll know this later */
 450                raw_pixel_start = pixel;
 451
 452                cmd_pixel_end = pixel + min(MAX_CMD_PIXELS + 1,
 453                        min((int)(pixel_end - pixel),
 454                            (int)(cmd_buffer_end - cmd) / bpp));
 455
 456                prefetch_range((void *) pixel, (cmd_pixel_end - pixel) * bpp);
 457
 458                while (pixel < cmd_pixel_end) {
 459                        const uint16_t * const repeating_pixel = pixel;
 460
 461                        *(uint16_t *)cmd = cpu_to_be16p(pixel);
 462                        cmd += 2;
 463                        pixel++;
 464
 465                        if (unlikely((pixel < cmd_pixel_end) &&
 466                                     (*pixel == *repeating_pixel))) {
 467                                /* go back and fill in raw pixel count */
 468                                *raw_pixels_count_byte = ((repeating_pixel -
 469                                                raw_pixel_start) + 1) & 0xFF;
 470
 471                                while ((pixel < cmd_pixel_end)
 472                                       && (*pixel == *repeating_pixel)) {
 473                                        pixel++;
 474                                }
 475
 476                                /* immediately after raw data is repeat byte */
 477                                *cmd++ = ((pixel - repeating_pixel) - 1) & 0xFF;
 478
 479                                /* Then start another raw pixel span */
 480                                raw_pixel_start = pixel;
 481                                raw_pixels_count_byte = cmd++;
 482                        }
 483                }
 484
 485                if (pixel > raw_pixel_start) {
 486                        /* finalize last RAW span */
 487                        *raw_pixels_count_byte = (pixel-raw_pixel_start) & 0xFF;
 488                }
 489
 490                *cmd_pixels_count_byte = (pixel - cmd_pixel_start) & 0xFF;
 491                dev_addr += (pixel - cmd_pixel_start) * bpp;
 492        }
 493
 494        if (cmd_buffer_end <= MIN_RLX_CMD_BYTES + cmd) {
 495                /* Fill leftover bytes with no-ops */
 496                if (cmd_buffer_end > cmd)
 497                        memset(cmd, 0xAF, cmd_buffer_end - cmd);
 498                cmd = (uint8_t *) cmd_buffer_end;
 499        }
 500
 501        *command_buffer_ptr = cmd;
 502        *pixel_start_ptr = pixel;
 503        *device_address_ptr = dev_addr;
 504
 505        return;
 506}
 507
 508/*
 509 * There are 3 copies of every pixel: The front buffer that the fbdev
 510 * client renders to, the actual framebuffer across the USB bus in hardware
 511 * (that we can only write to, slowly, and can never read), and (optionally)
 512 * our shadow copy that tracks what's been sent to that hardware buffer.
 513 */
 514static int dlfb_render_hline(struct dlfb_data *dev, struct urb **urb_ptr,
 515                              const char *front, char **urb_buf_ptr,
 516                              u32 byte_offset, u32 byte_width,
 517                              int *ident_ptr, int *sent_ptr)
 518{
 519        const u8 *line_start, *line_end, *next_pixel;
 520        u32 dev_addr = dev->base16 + byte_offset;
 521        struct urb *urb = *urb_ptr;
 522        u8 *cmd = *urb_buf_ptr;
 523        u8 *cmd_end = (u8 *) urb->transfer_buffer + urb->transfer_buffer_length;
 524
 525        line_start = (u8 *) (front + byte_offset);
 526        next_pixel = line_start;
 527        line_end = next_pixel + byte_width;
 528
 529        if (dev->backing_buffer) {
 530                int offset;
 531                const u8 *back_start = (u8 *) (dev->backing_buffer
 532                                                + byte_offset);
 533
 534                *ident_ptr += dlfb_trim_hline(back_start, &next_pixel,
 535                        &byte_width);
 536
 537                offset = next_pixel - line_start;
 538                line_end = next_pixel + byte_width;
 539                dev_addr += offset;
 540                back_start += offset;
 541                line_start += offset;
 542
 543                memcpy((char *)back_start, (char *) line_start,
 544                       byte_width);
 545        }
 546
 547        while (next_pixel < line_end) {
 548
 549                dlfb_compress_hline((const uint16_t **) &next_pixel,
 550                             (const uint16_t *) line_end, &dev_addr,
 551                        (u8 **) &cmd, (u8 *) cmd_end);
 552
 553                if (cmd >= cmd_end) {
 554                        int len = cmd - (u8 *) urb->transfer_buffer;
 555                        if (dlfb_submit_urb(dev, urb, len))
 556                                return 1; /* lost pixels is set */
 557                        *sent_ptr += len;
 558                        urb = dlfb_get_urb(dev);
 559                        if (!urb)
 560                                return 1; /* lost_pixels is set */
 561                        *urb_ptr = urb;
 562                        cmd = urb->transfer_buffer;
 563                        cmd_end = &cmd[urb->transfer_buffer_length];
 564                }
 565        }
 566
 567        *urb_buf_ptr = cmd;
 568
 569        return 0;
 570}
 571
 572int dlfb_handle_damage(struct dlfb_data *dev, int x, int y,
 573               int width, int height, char *data)
 574{
 575        int i, ret;
 576        char *cmd;
 577        cycles_t start_cycles, end_cycles;
 578        int bytes_sent = 0;
 579        int bytes_identical = 0;
 580        struct urb *urb;
 581        int aligned_x;
 582
 583        start_cycles = get_cycles();
 584
 585        aligned_x = DL_ALIGN_DOWN(x, sizeof(unsigned long));
 586        width = DL_ALIGN_UP(width + (x-aligned_x), sizeof(unsigned long));
 587        x = aligned_x;
 588
 589        if ((width <= 0) ||
 590            (x + width > dev->info->var.xres) ||
 591            (y + height > dev->info->var.yres))
 592                return -EINVAL;
 593
 594        if (!atomic_read(&dev->usb_active))
 595                return 0;
 596
 597        urb = dlfb_get_urb(dev);
 598        if (!urb)
 599                return 0;
 600        cmd = urb->transfer_buffer;
 601
 602        for (i = y; i < y + height ; i++) {
 603                const int line_offset = dev->info->fix.line_length * i;
 604                const int byte_offset = line_offset + (x * BPP);
 605
 606                if (dlfb_render_hline(dev, &urb,
 607                                      (char *) dev->info->fix.smem_start,
 608                                      &cmd, byte_offset, width * BPP,
 609                                      &bytes_identical, &bytes_sent))
 610                        goto error;
 611        }
 612
 613        if (cmd > (char *) urb->transfer_buffer) {
 614                /* Send partial buffer remaining before exiting */
 615                int len = cmd - (char *) urb->transfer_buffer;
 616                ret = dlfb_submit_urb(dev, urb, len);
 617                bytes_sent += len;
 618        } else
 619                dlfb_urb_completion(urb);
 620
 621error:
 622        atomic_add(bytes_sent, &dev->bytes_sent);
 623        atomic_add(bytes_identical, &dev->bytes_identical);
 624        atomic_add(width*height*2, &dev->bytes_rendered);
 625        end_cycles = get_cycles();
 626        atomic_add(((unsigned int) ((end_cycles - start_cycles)
 627                    >> 10)), /* Kcycles */
 628                   &dev->cpu_kcycles_used);
 629
 630        return 0;
 631}
 632
 633/*
 634 * Path triggered by usermode clients who write to filesystem
 635 * e.g. cat filename > /dev/fb1
 636 * Not used by X Windows or text-mode console. But useful for testing.
 637 * Slow because of extra copy and we must assume all pixels dirty.
 638 */
 639static ssize_t dlfb_ops_write(struct fb_info *info, const char __user *buf,
 640                          size_t count, loff_t *ppos)
 641{
 642        ssize_t result;
 643        struct dlfb_data *dev = info->par;
 644        u32 offset = (u32) *ppos;
 645
 646        result = fb_sys_write(info, buf, count, ppos);
 647
 648        if (result > 0) {
 649                int start = max((int)(offset / info->fix.line_length), 0);
 650                int lines = min((u32)((result / info->fix.line_length) + 1),
 651                                (u32)info->var.yres);
 652
 653                dlfb_handle_damage(dev, 0, start, info->var.xres,
 654                        lines, info->screen_base);
 655        }
 656
 657        return result;
 658}
 659
 660/* hardware has native COPY command (see libdlo), but not worth it for fbcon */
 661static void dlfb_ops_copyarea(struct fb_info *info,
 662                                const struct fb_copyarea *area)
 663{
 664
 665        struct dlfb_data *dev = info->par;
 666
 667        sys_copyarea(info, area);
 668
 669        dlfb_handle_damage(dev, area->dx, area->dy,
 670                        area->width, area->height, info->screen_base);
 671}
 672
 673static void dlfb_ops_imageblit(struct fb_info *info,
 674                                const struct fb_image *image)
 675{
 676        struct dlfb_data *dev = info->par;
 677
 678        sys_imageblit(info, image);
 679
 680        dlfb_handle_damage(dev, image->dx, image->dy,
 681                        image->width, image->height, info->screen_base);
 682}
 683
 684static void dlfb_ops_fillrect(struct fb_info *info,
 685                          const struct fb_fillrect *rect)
 686{
 687        struct dlfb_data *dev = info->par;
 688
 689        sys_fillrect(info, rect);
 690
 691        dlfb_handle_damage(dev, rect->dx, rect->dy, rect->width,
 692                              rect->height, info->screen_base);
 693}
 694
 695/*
 696 * NOTE: fb_defio.c is holding info->fbdefio.mutex
 697 *   Touching ANY framebuffer memory that triggers a page fault
 698 *   in fb_defio will cause a deadlock, when it also tries to
 699 *   grab the same mutex.
 700 */
 701static void dlfb_dpy_deferred_io(struct fb_info *info,
 702                                struct list_head *pagelist)
 703{
 704        struct page *cur;
 705        struct fb_deferred_io *fbdefio = info->fbdefio;
 706        struct dlfb_data *dev = info->par;
 707        struct urb *urb;
 708        char *cmd;
 709        cycles_t start_cycles, end_cycles;
 710        int bytes_sent = 0;
 711        int bytes_identical = 0;
 712        int bytes_rendered = 0;
 713
 714        if (!fb_defio)
 715                return;
 716
 717        if (!atomic_read(&dev->usb_active))
 718                return;
 719
 720        start_cycles = get_cycles();
 721
 722        urb = dlfb_get_urb(dev);
 723        if (!urb)
 724                return;
 725
 726        cmd = urb->transfer_buffer;
 727
 728        /* walk the written page list and render each to device */
 729        list_for_each_entry(cur, &fbdefio->pagelist, lru) {
 730
 731                if (dlfb_render_hline(dev, &urb, (char *) info->fix.smem_start,
 732                                  &cmd, cur->index << PAGE_SHIFT,
 733                                  PAGE_SIZE, &bytes_identical, &bytes_sent))
 734                        goto error;
 735                bytes_rendered += PAGE_SIZE;
 736        }
 737
 738        if (cmd > (char *) urb->transfer_buffer) {
 739                /* Send partial buffer remaining before exiting */
 740                int len = cmd - (char *) urb->transfer_buffer;
 741                dlfb_submit_urb(dev, urb, len);
 742                bytes_sent += len;
 743        } else
 744                dlfb_urb_completion(urb);
 745
 746error:
 747        atomic_add(bytes_sent, &dev->bytes_sent);
 748        atomic_add(bytes_identical, &dev->bytes_identical);
 749        atomic_add(bytes_rendered, &dev->bytes_rendered);
 750        end_cycles = get_cycles();
 751        atomic_add(((unsigned int) ((end_cycles - start_cycles)
 752                    >> 10)), /* Kcycles */
 753                   &dev->cpu_kcycles_used);
 754}
 755
 756static int dlfb_get_edid(struct dlfb_data *dev, char *edid, int len)
 757{
 758        int i;
 759        int ret;
 760        char *rbuf;
 761
 762        rbuf = kmalloc(2, GFP_KERNEL);
 763        if (!rbuf)
 764                return 0;
 765
 766        for (i = 0; i < len; i++) {
 767                ret = usb_control_msg(dev->udev,
 768                                    usb_rcvctrlpipe(dev->udev, 0), (0x02),
 769                                    (0x80 | (0x02 << 5)), i << 8, 0xA1, rbuf, 2,
 770                                    HZ);
 771                if (ret < 1) {
 772                        pr_err("Read EDID byte %d failed err %x\n", i, ret);
 773                        i--;
 774                        break;
 775                }
 776                edid[i] = rbuf[1];
 777        }
 778
 779        kfree(rbuf);
 780
 781        return i;
 782}
 783
 784static int dlfb_ops_ioctl(struct fb_info *info, unsigned int cmd,
 785                                unsigned long arg)
 786{
 787
 788        struct dlfb_data *dev = info->par;
 789
 790        if (!atomic_read(&dev->usb_active))
 791                return 0;
 792
 793        /* TODO: Update X server to get this from sysfs instead */
 794        if (cmd == DLFB_IOCTL_RETURN_EDID) {
 795                void __user *edid = (void __user *)arg;
 796                if (copy_to_user(edid, dev->edid, dev->edid_size))
 797                        return -EFAULT;
 798                return 0;
 799        }
 800
 801        /* TODO: Help propose a standard fb.h ioctl to report mmap damage */
 802        if (cmd == DLFB_IOCTL_REPORT_DAMAGE) {
 803                struct dloarea area;
 804
 805                if (copy_from_user(&area, (void __user *)arg,
 806                                  sizeof(struct dloarea)))
 807                        return -EFAULT;
 808
 809                /*
 810                 * If we have a damage-aware client, turn fb_defio "off"
 811                 * To avoid perf imact of unnecessary page fault handling.
 812                 * Done by resetting the delay for this fb_info to a very
 813                 * long period. Pages will become writable and stay that way.
 814                 * Reset to normal value when all clients have closed this fb.
 815                 */
 816                if (info->fbdefio)
 817                        info->fbdefio->delay = DL_DEFIO_WRITE_DISABLE;
 818
 819                if (area.x < 0)
 820                        area.x = 0;
 821
 822                if (area.x > info->var.xres)
 823                        area.x = info->var.xres;
 824
 825                if (area.y < 0)
 826                        area.y = 0;
 827
 828                if (area.y > info->var.yres)
 829                        area.y = info->var.yres;
 830
 831                dlfb_handle_damage(dev, area.x, area.y, area.w, area.h,
 832                           info->screen_base);
 833        }
 834
 835        return 0;
 836}
 837
 838/* taken from vesafb */
 839static int
 840dlfb_ops_setcolreg(unsigned regno, unsigned red, unsigned green,
 841               unsigned blue, unsigned transp, struct fb_info *info)
 842{
 843        int err = 0;
 844
 845        if (regno >= info->cmap.len)
 846                return 1;
 847
 848        if (regno < 16) {
 849                if (info->var.red.offset == 10) {
 850                        /* 1:5:5:5 */
 851                        ((u32 *) (info->pseudo_palette))[regno] =
 852                            ((red & 0xf800) >> 1) |
 853                            ((green & 0xf800) >> 6) | ((blue & 0xf800) >> 11);
 854                } else {
 855                        /* 0:5:6:5 */
 856                        ((u32 *) (info->pseudo_palette))[regno] =
 857                            ((red & 0xf800)) |
 858                            ((green & 0xfc00) >> 5) | ((blue & 0xf800) >> 11);
 859                }
 860        }
 861
 862        return err;
 863}
 864
 865/*
 866 * It's common for several clients to have framebuffer open simultaneously.
 867 * e.g. both fbcon and X. Makes things interesting.
 868 * Assumes caller is holding info->lock (for open and release at least)
 869 */
 870static int dlfb_ops_open(struct fb_info *info, int user)
 871{
 872        struct dlfb_data *dev = info->par;
 873
 874        /*
 875         * fbcon aggressively connects to first framebuffer it finds,
 876         * preventing other clients (X) from working properly. Usually
 877         * not what the user wants. Fail by default with option to enable.
 878         */
 879        if ((user == 0) && (!console))
 880                return -EBUSY;
 881
 882        /* If the USB device is gone, we don't accept new opens */
 883        if (dev->virtualized)
 884                return -ENODEV;
 885
 886        dev->fb_count++;
 887
 888        kref_get(&dev->kref);
 889
 890        if (fb_defio && (info->fbdefio == NULL)) {
 891                /* enable defio at last moment if not disabled by client */
 892
 893                struct fb_deferred_io *fbdefio;
 894
 895                fbdefio = kzalloc(sizeof(struct fb_deferred_io), GFP_KERNEL);
 896
 897                if (fbdefio) {
 898                        fbdefio->delay = DL_DEFIO_WRITE_DELAY;
 899                        fbdefio->deferred_io = dlfb_dpy_deferred_io;
 900                }
 901
 902                info->fbdefio = fbdefio;
 903                fb_deferred_io_init(info);
 904        }
 905
 906        pr_notice("open /dev/fb%d user=%d fb_info=%p count=%d\n",
 907            info->node, user, info, dev->fb_count);
 908
 909        return 0;
 910}
 911
 912/*
 913 * Called when all client interfaces to start transactions have been disabled,
 914 * and all references to our device instance (dlfb_data) are released.
 915 * Every transaction must have a reference, so we know are fully spun down
 916 */
 917static void dlfb_free(struct kref *kref)
 918{
 919        struct dlfb_data *dev = container_of(kref, struct dlfb_data, kref);
 920
 921        if (dev->backing_buffer)
 922                vfree(dev->backing_buffer);
 923
 924        kfree(dev->edid);
 925
 926        pr_warn("freeing dlfb_data %p\n", dev);
 927
 928        kfree(dev);
 929}
 930
 931static void dlfb_release_urb_work(struct work_struct *work)
 932{
 933        struct urb_node *unode = container_of(work, struct urb_node,
 934                                              release_urb_work.work);
 935
 936        up(&unode->dev->urbs.limit_sem);
 937}
 938
 939static void dlfb_free_framebuffer(struct dlfb_data *dev)
 940{
 941        struct fb_info *info = dev->info;
 942
 943        if (info) {
 944                int node = info->node;
 945
 946                unregister_framebuffer(info);
 947
 948                if (info->cmap.len != 0)
 949                        fb_dealloc_cmap(&info->cmap);
 950                if (info->monspecs.modedb)
 951                        fb_destroy_modedb(info->monspecs.modedb);
 952                if (info->screen_base)
 953                        vfree(info->screen_base);
 954
 955                fb_destroy_modelist(&info->modelist);
 956
 957                dev->info = NULL;
 958
 959                /* Assume info structure is freed after this point */
 960                framebuffer_release(info);
 961
 962                pr_warn("fb_info for /dev/fb%d has been freed\n", node);
 963        }
 964
 965        /* ref taken in probe() as part of registering framebfufer */
 966        kref_put(&dev->kref, dlfb_free);
 967}
 968
 969static void dlfb_free_framebuffer_work(struct work_struct *work)
 970{
 971        struct dlfb_data *dev = container_of(work, struct dlfb_data,
 972                                             free_framebuffer_work.work);
 973        dlfb_free_framebuffer(dev);
 974}
 975/*
 976 * Assumes caller is holding info->lock mutex (for open and release at least)
 977 */
 978static int dlfb_ops_release(struct fb_info *info, int user)
 979{
 980        struct dlfb_data *dev = info->par;
 981
 982        dev->fb_count--;
 983
 984        /* We can't free fb_info here - fbmem will touch it when we return */
 985        if (dev->virtualized && (dev->fb_count == 0))
 986                schedule_delayed_work(&dev->free_framebuffer_work, HZ);
 987
 988        if ((dev->fb_count == 0) && (info->fbdefio)) {
 989                fb_deferred_io_cleanup(info);
 990                kfree(info->fbdefio);
 991                info->fbdefio = NULL;
 992                info->fbops->fb_mmap = dlfb_ops_mmap;
 993        }
 994
 995        pr_warn("released /dev/fb%d user=%d count=%d\n",
 996                  info->node, user, dev->fb_count);
 997
 998        kref_put(&dev->kref, dlfb_free);
 999
1000        return 0;
1001}
1002
1003/*
1004 * Check whether a video mode is supported by the DisplayLink chip
1005 * We start from monitor's modes, so don't need to filter that here
1006 */
1007static int dlfb_is_valid_mode(struct fb_videomode *mode,
1008                struct fb_info *info)
1009{
1010        struct dlfb_data *dev = info->par;
1011
1012        if (mode->xres * mode->yres > dev->sku_pixel_limit) {
1013                pr_warn("%dx%d beyond chip capabilities\n",
1014                       mode->xres, mode->yres);
1015                return 0;
1016        }
1017
1018        pr_info("%dx%d @ %d Hz valid mode\n", mode->xres, mode->yres,
1019                mode->refresh);
1020
1021        return 1;
1022}
1023
1024static void dlfb_var_color_format(struct fb_var_screeninfo *var)
1025{
1026        const struct fb_bitfield red = { 11, 5, 0 };
1027        const struct fb_bitfield green = { 5, 6, 0 };
1028        const struct fb_bitfield blue = { 0, 5, 0 };
1029
1030        var->bits_per_pixel = 16;
1031        var->red = red;
1032        var->green = green;
1033        var->blue = blue;
1034}
1035
1036static int dlfb_ops_check_var(struct fb_var_screeninfo *var,
1037                                struct fb_info *info)
1038{
1039        struct fb_videomode mode;
1040
1041        /* TODO: support dynamically changing framebuffer size */
1042        if ((var->xres * var->yres * 2) > info->fix.smem_len)
1043                return -EINVAL;
1044
1045        /* set device-specific elements of var unrelated to mode */
1046        dlfb_var_color_format(var);
1047
1048        fb_var_to_videomode(&mode, var);
1049
1050        if (!dlfb_is_valid_mode(&mode, info))
1051                return -EINVAL;
1052
1053        return 0;
1054}
1055
1056static int dlfb_ops_set_par(struct fb_info *info)
1057{
1058        struct dlfb_data *dev = info->par;
1059        int result;
1060        u16 *pix_framebuffer;
1061        int i;
1062
1063        pr_notice("set_par mode %dx%d\n", info->var.xres, info->var.yres);
1064
1065        result = dlfb_set_video_mode(dev, &info->var);
1066
1067        if ((result == 0) && (dev->fb_count == 0)) {
1068
1069                /* paint greenscreen */
1070
1071                pix_framebuffer = (u16 *) info->screen_base;
1072                for (i = 0; i < info->fix.smem_len / 2; i++)
1073                        pix_framebuffer[i] = 0x37e6;
1074
1075                dlfb_handle_damage(dev, 0, 0, info->var.xres, info->var.yres,
1076                                   info->screen_base);
1077        }
1078
1079        return result;
1080}
1081
1082/* To fonzi the jukebox (e.g. make blanking changes take effect) */
1083static char *dlfb_dummy_render(char *buf)
1084{
1085        *buf++ = 0xAF;
1086        *buf++ = 0x6A; /* copy */
1087        *buf++ = 0x00; /* from address*/
1088        *buf++ = 0x00;
1089        *buf++ = 0x00;
1090        *buf++ = 0x01; /* one pixel */
1091        *buf++ = 0x00; /* to address */
1092        *buf++ = 0x00;
1093        *buf++ = 0x00;
1094        return buf;
1095}
1096
1097/*
1098 * In order to come back from full DPMS off, we need to set the mode again
1099 */
1100static int dlfb_ops_blank(int blank_mode, struct fb_info *info)
1101{
1102        struct dlfb_data *dev = info->par;
1103        char *bufptr;
1104        struct urb *urb;
1105
1106        pr_info("/dev/fb%d FB_BLANK mode %d --> %d\n",
1107                info->node, dev->blank_mode, blank_mode);
1108
1109        if ((dev->blank_mode == FB_BLANK_POWERDOWN) &&
1110            (blank_mode != FB_BLANK_POWERDOWN)) {
1111
1112                /* returning from powerdown requires a fresh modeset */
1113                dlfb_set_video_mode(dev, &info->var);
1114        }
1115
1116        urb = dlfb_get_urb(dev);
1117        if (!urb)
1118                return 0;
1119
1120        bufptr = (char *) urb->transfer_buffer;
1121        bufptr = dlfb_vidreg_lock(bufptr);
1122        bufptr = dlfb_blanking(bufptr, blank_mode);
1123        bufptr = dlfb_vidreg_unlock(bufptr);
1124
1125        /* seems like a render op is needed to have blank change take effect */
1126        bufptr = dlfb_dummy_render(bufptr);
1127
1128        dlfb_submit_urb(dev, urb, bufptr -
1129                        (char *) urb->transfer_buffer);
1130
1131        dev->blank_mode = blank_mode;
1132
1133        return 0;
1134}
1135
1136static struct fb_ops dlfb_ops = {
1137        .owner = THIS_MODULE,
1138        .fb_read = fb_sys_read,
1139        .fb_write = dlfb_ops_write,
1140        .fb_setcolreg = dlfb_ops_setcolreg,
1141        .fb_fillrect = dlfb_ops_fillrect,
1142        .fb_copyarea = dlfb_ops_copyarea,
1143        .fb_imageblit = dlfb_ops_imageblit,
1144        .fb_mmap = dlfb_ops_mmap,
1145        .fb_ioctl = dlfb_ops_ioctl,
1146        .fb_open = dlfb_ops_open,
1147        .fb_release = dlfb_ops_release,
1148        .fb_blank = dlfb_ops_blank,
1149        .fb_check_var = dlfb_ops_check_var,
1150        .fb_set_par = dlfb_ops_set_par,
1151};
1152
1153
1154/*
1155 * Assumes &info->lock held by caller
1156 * Assumes no active clients have framebuffer open
1157 */
1158static int dlfb_realloc_framebuffer(struct dlfb_data *dev, struct fb_info *info)
1159{
1160        int retval = -ENOMEM;
1161        int old_len = info->fix.smem_len;
1162        int new_len;
1163        unsigned char *old_fb = info->screen_base;
1164        unsigned char *new_fb;
1165        unsigned char *new_back = 0;
1166
1167        pr_warn("Reallocating framebuffer. Addresses will change!\n");
1168
1169        new_len = info->fix.line_length * info->var.yres;
1170
1171        if (PAGE_ALIGN(new_len) > old_len) {
1172                /*
1173                 * Alloc system memory for virtual framebuffer
1174                 */
1175                new_fb = vmalloc(new_len);
1176                if (!new_fb) {
1177                        pr_err("Virtual framebuffer alloc failed\n");
1178                        goto error;
1179                }
1180
1181                if (info->screen_base) {
1182                        memcpy(new_fb, old_fb, old_len);
1183                        vfree(info->screen_base);
1184                }
1185
1186                info->screen_base = new_fb;
1187                info->fix.smem_len = PAGE_ALIGN(new_len);
1188                info->fix.smem_start = (unsigned long) new_fb;
1189                info->flags = udlfb_info_flags;
1190
1191                /*
1192                 * Second framebuffer copy to mirror the framebuffer state
1193                 * on the physical USB device. We can function without this.
1194                 * But with imperfect damage info we may send pixels over USB
1195                 * that were, in fact, unchanged - wasting limited USB bandwidth
1196                 */
1197                if (shadow)
1198                        new_back = vzalloc(new_len);
1199                if (!new_back)
1200                        pr_info("No shadow/backing buffer allocated\n");
1201                else {
1202                        if (dev->backing_buffer)
1203                                vfree(dev->backing_buffer);
1204                        dev->backing_buffer = new_back;
1205                }
1206        }
1207
1208        retval = 0;
1209
1210error:
1211        return retval;
1212}
1213
1214/*
1215 * 1) Get EDID from hw, or use sw default
1216 * 2) Parse into various fb_info structs
1217 * 3) Allocate virtual framebuffer memory to back highest res mode
1218 *
1219 * Parses EDID into three places used by various parts of fbdev:
1220 * fb_var_screeninfo contains the timing of the monitor's preferred mode
1221 * fb_info.monspecs is full parsed EDID info, including monspecs.modedb
1222 * fb_info.modelist is a linked list of all monitor & VESA modes which work
1223 *
1224 * If EDID is not readable/valid, then modelist is all VESA modes,
1225 * monspecs is NULL, and fb_var_screeninfo is set to safe VESA mode
1226 * Returns 0 if successful
1227 */
1228static int dlfb_setup_modes(struct dlfb_data *dev,
1229                           struct fb_info *info,
1230                           char *default_edid, size_t default_edid_size)
1231{
1232        int i;
1233        const struct fb_videomode *default_vmode = NULL;
1234        int result = 0;
1235        char *edid;
1236        int tries = 3;
1237
1238        if (info->dev) /* only use mutex if info has been registered */
1239                mutex_lock(&info->lock);
1240
1241        edid = kmalloc(EDID_LENGTH, GFP_KERNEL);
1242        if (!edid) {
1243                result = -ENOMEM;
1244                goto error;
1245        }
1246
1247        fb_destroy_modelist(&info->modelist);
1248        memset(&info->monspecs, 0, sizeof(info->monspecs));
1249
1250        /*
1251         * Try to (re)read EDID from hardware first
1252         * EDID data may return, but not parse as valid
1253         * Try again a few times, in case of e.g. analog cable noise
1254         */
1255        while (tries--) {
1256
1257                i = dlfb_get_edid(dev, edid, EDID_LENGTH);
1258
1259                if (i >= EDID_LENGTH)
1260                        fb_edid_to_monspecs(edid, &info->monspecs);
1261
1262                if (info->monspecs.modedb_len > 0) {
1263                        dev->edid = edid;
1264                        dev->edid_size = i;
1265                        break;
1266                }
1267        }
1268
1269        /* If that fails, use a previously returned EDID if available */
1270        if (info->monspecs.modedb_len == 0) {
1271
1272                pr_err("Unable to get valid EDID from device/display\n");
1273
1274                if (dev->edid) {
1275                        fb_edid_to_monspecs(dev->edid, &info->monspecs);
1276                        if (info->monspecs.modedb_len > 0)
1277                                pr_err("Using previously queried EDID\n");
1278                }
1279        }
1280
1281        /* If that fails, use the default EDID we were handed */
1282        if (info->monspecs.modedb_len == 0) {
1283                if (default_edid_size >= EDID_LENGTH) {
1284                        fb_edid_to_monspecs(default_edid, &info->monspecs);
1285                        if (info->monspecs.modedb_len > 0) {
1286                                memcpy(edid, default_edid, default_edid_size);
1287                                dev->edid = edid;
1288                                dev->edid_size = default_edid_size;
1289                                pr_err("Using default/backup EDID\n");
1290                        }
1291                }
1292        }
1293
1294        /* If we've got modes, let's pick a best default mode */
1295        if (info->monspecs.modedb_len > 0) {
1296
1297                for (i = 0; i < info->monspecs.modedb_len; i++) {
1298                        if (dlfb_is_valid_mode(&info->monspecs.modedb[i], info))
1299                                fb_add_videomode(&info->monspecs.modedb[i],
1300                                        &info->modelist);
1301                        else {
1302                                if (i == 0)
1303                                        /* if we've removed top/best mode */
1304                                        info->monspecs.misc
1305                                                &= ~FB_MISC_1ST_DETAIL;
1306                        }
1307                }
1308
1309                default_vmode = fb_find_best_display(&info->monspecs,
1310                                                     &info->modelist);
1311        }
1312
1313        /* If everything else has failed, fall back to safe default mode */
1314        if (default_vmode == NULL) {
1315
1316                struct fb_videomode fb_vmode = {0};
1317
1318                /*
1319                 * Add the standard VESA modes to our modelist
1320                 * Since we don't have EDID, there may be modes that
1321                 * overspec monitor and/or are incorrect aspect ratio, etc.
1322                 * But at least the user has a chance to choose
1323                 */
1324                for (i = 0; i < VESA_MODEDB_SIZE; i++) {
1325                        if (dlfb_is_valid_mode((struct fb_videomode *)
1326                                                &vesa_modes[i], info))
1327                                fb_add_videomode(&vesa_modes[i],
1328                                                 &info->modelist);
1329                }
1330
1331                /*
1332                 * default to resolution safe for projectors
1333                 * (since they are most common case without EDID)
1334                 */
1335                fb_vmode.xres = 800;
1336                fb_vmode.yres = 600;
1337                fb_vmode.refresh = 60;
1338                default_vmode = fb_find_nearest_mode(&fb_vmode,
1339                                                     &info->modelist);
1340        }
1341
1342        /* If we have good mode and no active clients*/
1343        if ((default_vmode != NULL) && (dev->fb_count == 0)) {
1344
1345                fb_videomode_to_var(&info->var, default_vmode);
1346                dlfb_var_color_format(&info->var);
1347
1348                /*
1349                 * with mode size info, we can now alloc our framebuffer.
1350                 */
1351                memcpy(&info->fix, &dlfb_fix, sizeof(dlfb_fix));
1352                info->fix.line_length = info->var.xres *
1353                        (info->var.bits_per_pixel / 8);
1354
1355                result = dlfb_realloc_framebuffer(dev, info);
1356
1357        } else
1358                result = -EINVAL;
1359
1360error:
1361        if (edid && (dev->edid != edid))
1362                kfree(edid);
1363
1364        if (info->dev)
1365                mutex_unlock(&info->lock);
1366
1367        return result;
1368}
1369
1370static ssize_t metrics_bytes_rendered_show(struct device *fbdev,
1371                                   struct device_attribute *a, char *buf) {
1372        struct fb_info *fb_info = dev_get_drvdata(fbdev);
1373        struct dlfb_data *dev = fb_info->par;
1374        return snprintf(buf, PAGE_SIZE, "%u\n",
1375                        atomic_read(&dev->bytes_rendered));
1376}
1377
1378static ssize_t metrics_bytes_identical_show(struct device *fbdev,
1379                                   struct device_attribute *a, char *buf) {
1380        struct fb_info *fb_info = dev_get_drvdata(fbdev);
1381        struct dlfb_data *dev = fb_info->par;
1382        return snprintf(buf, PAGE_SIZE, "%u\n",
1383                        atomic_read(&dev->bytes_identical));
1384}
1385
1386static ssize_t metrics_bytes_sent_show(struct device *fbdev,
1387                                   struct device_attribute *a, char *buf) {
1388        struct fb_info *fb_info = dev_get_drvdata(fbdev);
1389        struct dlfb_data *dev = fb_info->par;
1390        return snprintf(buf, PAGE_SIZE, "%u\n",
1391                        atomic_read(&dev->bytes_sent));
1392}
1393
1394static ssize_t metrics_cpu_kcycles_used_show(struct device *fbdev,
1395                                   struct device_attribute *a, char *buf) {
1396        struct fb_info *fb_info = dev_get_drvdata(fbdev);
1397        struct dlfb_data *dev = fb_info->par;
1398        return snprintf(buf, PAGE_SIZE, "%u\n",
1399                        atomic_read(&dev->cpu_kcycles_used));
1400}
1401
1402static ssize_t edid_show(
1403                        struct file *filp,
1404                        struct kobject *kobj, struct bin_attribute *a,
1405                         char *buf, loff_t off, size_t count) {
1406        struct device *fbdev = container_of(kobj, struct device, kobj);
1407        struct fb_info *fb_info = dev_get_drvdata(fbdev);
1408        struct dlfb_data *dev = fb_info->par;
1409
1410        if (dev->edid == NULL)
1411                return 0;
1412
1413        if ((off >= dev->edid_size) || (count > dev->edid_size))
1414                return 0;
1415
1416        if (off + count > dev->edid_size)
1417                count = dev->edid_size - off;
1418
1419        pr_info("sysfs edid copy %p to %p, %d bytes\n",
1420                dev->edid, buf, (int) count);
1421
1422        memcpy(buf, dev->edid, count);
1423
1424        return count;
1425}
1426
1427static ssize_t edid_store(
1428                        struct file *filp,
1429                        struct kobject *kobj, struct bin_attribute *a,
1430                        char *src, loff_t src_off, size_t src_size) {
1431        struct device *fbdev = container_of(kobj, struct device, kobj);
1432        struct fb_info *fb_info = dev_get_drvdata(fbdev);
1433        struct dlfb_data *dev = fb_info->par;
1434        int ret;
1435
1436        /* We only support write of entire EDID at once, no offset*/
1437        if ((src_size != EDID_LENGTH) || (src_off != 0))
1438                return -EINVAL;
1439
1440        ret = dlfb_setup_modes(dev, fb_info, src, src_size);
1441        if (ret)
1442                return ret;
1443
1444        if (!dev->edid || memcmp(src, dev->edid, src_size))
1445                return -EINVAL;
1446
1447        pr_info("sysfs written EDID is new default\n");
1448        dlfb_ops_set_par(fb_info);
1449        return src_size;
1450}
1451
1452static ssize_t metrics_reset_store(struct device *fbdev,
1453                           struct device_attribute *attr,
1454                           const char *buf, size_t count)
1455{
1456        struct fb_info *fb_info = dev_get_drvdata(fbdev);
1457        struct dlfb_data *dev = fb_info->par;
1458
1459        atomic_set(&dev->bytes_rendered, 0);
1460        atomic_set(&dev->bytes_identical, 0);
1461        atomic_set(&dev->bytes_sent, 0);
1462        atomic_set(&dev->cpu_kcycles_used, 0);
1463
1464        return count;
1465}
1466
1467static struct bin_attribute edid_attr = {
1468        .attr.name = "edid",
1469        .attr.mode = 0666,
1470        .size = EDID_LENGTH,
1471        .read = edid_show,
1472        .write = edid_store
1473};
1474
1475static struct device_attribute fb_device_attrs[] = {
1476        __ATTR_RO(metrics_bytes_rendered),
1477        __ATTR_RO(metrics_bytes_identical),
1478        __ATTR_RO(metrics_bytes_sent),
1479        __ATTR_RO(metrics_cpu_kcycles_used),
1480        __ATTR(metrics_reset, S_IWUSR, NULL, metrics_reset_store),
1481};
1482
1483/*
1484 * This is necessary before we can communicate with the display controller.
1485 */
1486static int dlfb_select_std_channel(struct dlfb_data *dev)
1487{
1488        int ret;
1489        u8 set_def_chn[] = {       0x57, 0xCD, 0xDC, 0xA7,
1490                                0x1C, 0x88, 0x5E, 0x15,
1491                                0x60, 0xFE, 0xC6, 0x97,
1492                                0x16, 0x3D, 0x47, 0xF2  };
1493
1494        ret = usb_control_msg(dev->udev, usb_sndctrlpipe(dev->udev, 0),
1495                        NR_USB_REQUEST_CHANNEL,
1496                        (USB_DIR_OUT | USB_TYPE_VENDOR), 0, 0,
1497                        set_def_chn, sizeof(set_def_chn), USB_CTRL_SET_TIMEOUT);
1498        return ret;
1499}
1500
1501static int dlfb_parse_vendor_descriptor(struct dlfb_data *dev,
1502                                        struct usb_interface *interface)
1503{
1504        char *desc;
1505        char *buf;
1506        char *desc_end;
1507
1508        int total_len = 0;
1509
1510        buf = kzalloc(MAX_VENDOR_DESCRIPTOR_SIZE, GFP_KERNEL);
1511        if (!buf)
1512                return false;
1513        desc = buf;
1514
1515        total_len = usb_get_descriptor(interface_to_usbdev(interface),
1516                                        0x5f, /* vendor specific */
1517                                        0, desc, MAX_VENDOR_DESCRIPTOR_SIZE);
1518
1519        /* if not found, look in configuration descriptor */
1520        if (total_len < 0) {
1521                if (0 == usb_get_extra_descriptor(interface->cur_altsetting,
1522                        0x5f, &desc))
1523                        total_len = (int) desc[0];
1524        }
1525
1526        if (total_len > 5) {
1527                pr_info("vendor descriptor length:%x data:%02x %02x %02x %02x" \
1528                        "%02x %02x %02x %02x %02x %02x %02x\n",
1529                        total_len, desc[0],
1530                        desc[1], desc[2], desc[3], desc[4], desc[5], desc[6],
1531                        desc[7], desc[8], desc[9], desc[10]);
1532
1533                if ((desc[0] != total_len) || /* descriptor length */
1534                    (desc[1] != 0x5f) ||   /* vendor descriptor type */
1535                    (desc[2] != 0x01) ||   /* version (2 bytes) */
1536                    (desc[3] != 0x00) ||
1537                    (desc[4] != total_len - 2)) /* length after type */
1538                        goto unrecognized;
1539
1540                desc_end = desc + total_len;
1541                desc += 5; /* the fixed header we've already parsed */
1542
1543                while (desc < desc_end) {
1544                        u8 length;
1545                        u16 key;
1546
1547                        key = le16_to_cpu(*((u16 *) desc));
1548                        desc += sizeof(u16);
1549                        length = *desc;
1550                        desc++;
1551
1552                        switch (key) {
1553                        case 0x0200: { /* max_area */
1554                                u32 max_area;
1555                                max_area = le32_to_cpu(*((u32 *)desc));
1556                                pr_warn("DL chip limited to %d pixel modes\n",
1557                                        max_area);
1558                                dev->sku_pixel_limit = max_area;
1559                                break;
1560                        }
1561                        default:
1562                                break;
1563                        }
1564                        desc += length;
1565                }
1566        } else {
1567                pr_info("vendor descriptor not available (%d)\n", total_len);
1568        }
1569
1570        goto success;
1571
1572unrecognized:
1573        /* allow udlfb to load for now even if firmware unrecognized */
1574        pr_err("Unrecognized vendor firmware descriptor\n");
1575
1576success:
1577        kfree(buf);
1578        return true;
1579}
1580
1581static void dlfb_init_framebuffer_work(struct work_struct *work);
1582
1583static int dlfb_usb_probe(struct usb_interface *interface,
1584                        const struct usb_device_id *id)
1585{
1586        struct usb_device *usbdev;
1587        struct dlfb_data *dev = 0;
1588        int retval = -ENOMEM;
1589
1590        /* usb initialization */
1591
1592        usbdev = interface_to_usbdev(interface);
1593
1594        dev = kzalloc(sizeof(*dev), GFP_KERNEL);
1595        if (dev == NULL) {
1596                dev_err(&interface->dev, "dlfb_usb_probe: failed alloc of dev struct\n");
1597                goto error;
1598        }
1599
1600        kref_init(&dev->kref); /* matching kref_put in usb .disconnect fn */
1601
1602        dev->udev = usbdev;
1603        dev->gdev = &usbdev->dev; /* our generic struct device * */
1604        usb_set_intfdata(interface, dev);
1605
1606        pr_info("%s %s - serial #%s\n",
1607                usbdev->manufacturer, usbdev->product, usbdev->serial);
1608        pr_info("vid_%04x&pid_%04x&rev_%04x driver's dlfb_data struct at %p\n",
1609                usbdev->descriptor.idVendor, usbdev->descriptor.idProduct,
1610                usbdev->descriptor.bcdDevice, dev);
1611        pr_info("console enable=%d\n", console);
1612        pr_info("fb_defio enable=%d\n", fb_defio);
1613        pr_info("shadow enable=%d\n", shadow);
1614
1615        dev->sku_pixel_limit = 2048 * 1152; /* default to maximum */
1616
1617        if (!dlfb_parse_vendor_descriptor(dev, interface)) {
1618                pr_err("firmware not recognized. Assume incompatible device\n");
1619                goto error;
1620        }
1621
1622        if (pixel_limit) {
1623                pr_warn("DL chip limit of %d overriden"
1624                        " by module param to %d\n",
1625                        dev->sku_pixel_limit, pixel_limit);
1626                dev->sku_pixel_limit = pixel_limit;
1627        }
1628
1629
1630        if (!dlfb_alloc_urb_list(dev, WRITES_IN_FLIGHT, MAX_TRANSFER)) {
1631                retval = -ENOMEM;
1632                pr_err("dlfb_alloc_urb_list failed\n");
1633                goto error;
1634        }
1635
1636        kref_get(&dev->kref); /* matching kref_put in free_framebuffer_work */
1637
1638        /* We don't register a new USB class. Our client interface is fbdev */
1639
1640        /* Workitem keep things fast & simple during USB enumeration */
1641        INIT_DELAYED_WORK(&dev->init_framebuffer_work,
1642                          dlfb_init_framebuffer_work);
1643        schedule_delayed_work(&dev->init_framebuffer_work, 0);
1644
1645        return 0;
1646
1647error:
1648        if (dev) {
1649
1650                kref_put(&dev->kref, dlfb_free); /* ref for framebuffer */
1651                kref_put(&dev->kref, dlfb_free); /* last ref from kref_init */
1652
1653                /* dev has been deallocated. Do not dereference */
1654        }
1655
1656        return retval;
1657}
1658
1659static void dlfb_init_framebuffer_work(struct work_struct *work)
1660{
1661        struct dlfb_data *dev = container_of(work, struct dlfb_data,
1662                                             init_framebuffer_work.work);
1663        struct fb_info *info;
1664        int retval;
1665        int i;
1666
1667        /* allocates framebuffer driver structure, not framebuffer memory */
1668        info = framebuffer_alloc(0, dev->gdev);
1669        if (!info) {
1670                retval = -ENOMEM;
1671                pr_err("framebuffer_alloc failed\n");
1672                goto error;
1673        }
1674
1675        dev->info = info;
1676        info->par = dev;
1677        info->pseudo_palette = dev->pseudo_palette;
1678        info->fbops = &dlfb_ops;
1679
1680        retval = fb_alloc_cmap(&info->cmap, 256, 0);
1681        if (retval < 0) {
1682                pr_err("fb_alloc_cmap failed %x\n", retval);
1683                goto error;
1684        }
1685
1686        INIT_DELAYED_WORK(&dev->free_framebuffer_work,
1687                          dlfb_free_framebuffer_work);
1688
1689        INIT_LIST_HEAD(&info->modelist);
1690
1691        retval = dlfb_setup_modes(dev, info, NULL, 0);
1692        if (retval != 0) {
1693                pr_err("unable to find common mode for display and adapter\n");
1694                goto error;
1695        }
1696
1697        /* ready to begin using device */
1698
1699        atomic_set(&dev->usb_active, 1);
1700        dlfb_select_std_channel(dev);
1701
1702        dlfb_ops_check_var(&info->var, info);
1703        dlfb_ops_set_par(info);
1704
1705        retval = register_framebuffer(info);
1706        if (retval < 0) {
1707                pr_err("register_framebuffer failed %d\n", retval);
1708                goto error;
1709        }
1710
1711        for (i = 0; i < ARRAY_SIZE(fb_device_attrs); i++) {
1712                retval = device_create_file(info->dev, &fb_device_attrs[i]);
1713                if (retval) {
1714                        pr_warn("device_create_file failed %d\n", retval);
1715                }
1716        }
1717
1718        retval = device_create_bin_file(info->dev, &edid_attr);
1719        if (retval) {
1720                pr_warn("device_create_bin_file failed %d\n", retval);
1721        }
1722
1723        pr_info("DisplayLink USB device /dev/fb%d attached. %dx%d resolution."
1724                        " Using %dK framebuffer memory\n", info->node,
1725                        info->var.xres, info->var.yres,
1726                        ((dev->backing_buffer) ?
1727                        info->fix.smem_len * 2 : info->fix.smem_len) >> 10);
1728        return;
1729
1730error:
1731        dlfb_free_framebuffer(dev);
1732}
1733
1734static void dlfb_usb_disconnect(struct usb_interface *interface)
1735{
1736        struct dlfb_data *dev;
1737        struct fb_info *info;
1738        int i;
1739
1740        dev = usb_get_intfdata(interface);
1741        info = dev->info;
1742
1743        pr_info("USB disconnect starting\n");
1744
1745        /* we virtualize until all fb clients release. Then we free */
1746        dev->virtualized = true;
1747
1748        /* When non-active we'll update virtual framebuffer, but no new urbs */
1749        atomic_set(&dev->usb_active, 0);
1750
1751        /* this function will wait for all in-flight urbs to complete */
1752        dlfb_free_urb_list(dev);
1753
1754        if (info) {
1755                /* remove udlfb's sysfs interfaces */
1756                for (i = 0; i < ARRAY_SIZE(fb_device_attrs); i++)
1757                        device_remove_file(info->dev, &fb_device_attrs[i]);
1758                device_remove_bin_file(info->dev, &edid_attr);
1759                unlink_framebuffer(info);
1760        }
1761
1762        usb_set_intfdata(interface, NULL);
1763        dev->udev = NULL;
1764        dev->gdev = NULL;
1765
1766        /* if clients still have us open, will be freed on last close */
1767        if (dev->fb_count == 0)
1768                schedule_delayed_work(&dev->free_framebuffer_work, 0);
1769
1770        /* release reference taken by kref_init in probe() */
1771        kref_put(&dev->kref, dlfb_free);
1772
1773        /* consider dlfb_data freed */
1774
1775        return;
1776}
1777
1778static struct usb_driver dlfb_driver = {
1779        .name = "udlfb",
1780        .probe = dlfb_usb_probe,
1781        .disconnect = dlfb_usb_disconnect,
1782        .id_table = id_table,
1783};
1784
1785module_usb_driver(dlfb_driver);
1786
1787static void dlfb_urb_completion(struct urb *urb)
1788{
1789        struct urb_node *unode = urb->context;
1790        struct dlfb_data *dev = unode->dev;
1791        unsigned long flags;
1792
1793        /* sync/async unlink faults aren't errors */
1794        if (urb->status) {
1795                if (!(urb->status == -ENOENT ||
1796                    urb->status == -ECONNRESET ||
1797                    urb->status == -ESHUTDOWN)) {
1798                        pr_err("%s - nonzero write bulk status received: %d\n",
1799                                __func__, urb->status);
1800                        atomic_set(&dev->lost_pixels, 1);
1801                }
1802        }
1803
1804        urb->transfer_buffer_length = dev->urbs.size; /* reset to actual */
1805
1806        spin_lock_irqsave(&dev->urbs.lock, flags);
1807        list_add_tail(&unode->entry, &dev->urbs.list);
1808        dev->urbs.available++;
1809        spin_unlock_irqrestore(&dev->urbs.lock, flags);
1810
1811        /*
1812         * When using fb_defio, we deadlock if up() is called
1813         * while another is waiting. So queue to another process.
1814         */
1815        if (fb_defio)
1816                schedule_delayed_work(&unode->release_urb_work, 0);
1817        else
1818                up(&dev->urbs.limit_sem);
1819}
1820
1821static void dlfb_free_urb_list(struct dlfb_data *dev)
1822{
1823        int count = dev->urbs.count;
1824        struct list_head *node;
1825        struct urb_node *unode;
1826        struct urb *urb;
1827        int ret;
1828        unsigned long flags;
1829
1830        pr_notice("Freeing all render urbs\n");
1831
1832        /* keep waiting and freeing, until we've got 'em all */
1833        while (count--) {
1834
1835                /* Getting interrupted means a leak, but ok at disconnect */
1836                ret = down_interruptible(&dev->urbs.limit_sem);
1837                if (ret)
1838                        break;
1839
1840                spin_lock_irqsave(&dev->urbs.lock, flags);
1841
1842                node = dev->urbs.list.next; /* have reserved one with sem */
1843                list_del_init(node);
1844
1845                spin_unlock_irqrestore(&dev->urbs.lock, flags);
1846
1847                unode = list_entry(node, struct urb_node, entry);
1848                urb = unode->urb;
1849
1850                /* Free each separately allocated piece */
1851                usb_free_coherent(urb->dev, dev->urbs.size,
1852                                  urb->transfer_buffer, urb->transfer_dma);
1853                usb_free_urb(urb);
1854                kfree(node);
1855        }
1856
1857        dev->urbs.count = 0;
1858}
1859
1860static int dlfb_alloc_urb_list(struct dlfb_data *dev, int count, size_t size)
1861{
1862        int i = 0;
1863        struct urb *urb;
1864        struct urb_node *unode;
1865        char *buf;
1866
1867        spin_lock_init(&dev->urbs.lock);
1868
1869        dev->urbs.size = size;
1870        INIT_LIST_HEAD(&dev->urbs.list);
1871
1872        while (i < count) {
1873                unode = kzalloc(sizeof(struct urb_node), GFP_KERNEL);
1874                if (!unode)
1875                        break;
1876                unode->dev = dev;
1877
1878                INIT_DELAYED_WORK(&unode->release_urb_work,
1879                          dlfb_release_urb_work);
1880
1881                urb = usb_alloc_urb(0, GFP_KERNEL);
1882                if (!urb) {
1883                        kfree(unode);
1884                        break;
1885                }
1886                unode->urb = urb;
1887
1888                buf = usb_alloc_coherent(dev->udev, MAX_TRANSFER, GFP_KERNEL,
1889                                         &urb->transfer_dma);
1890                if (!buf) {
1891                        kfree(unode);
1892                        usb_free_urb(urb);
1893                        break;
1894                }
1895
1896                /* urb->transfer_buffer_length set to actual before submit */
1897                usb_fill_bulk_urb(urb, dev->udev, usb_sndbulkpipe(dev->udev, 1),
1898                        buf, size, dlfb_urb_completion, unode);
1899                urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
1900
1901                list_add_tail(&unode->entry, &dev->urbs.list);
1902
1903                i++;
1904        }
1905
1906        sema_init(&dev->urbs.limit_sem, i);
1907        dev->urbs.count = i;
1908        dev->urbs.available = i;
1909
1910        pr_notice("allocated %d %d byte urbs\n", i, (int) size);
1911
1912        return i;
1913}
1914
1915static struct urb *dlfb_get_urb(struct dlfb_data *dev)
1916{
1917        int ret = 0;
1918        struct list_head *entry;
1919        struct urb_node *unode;
1920        struct urb *urb = NULL;
1921        unsigned long flags;
1922
1923        /* Wait for an in-flight buffer to complete and get re-queued */
1924        ret = down_timeout(&dev->urbs.limit_sem, GET_URB_TIMEOUT);
1925        if (ret) {
1926                atomic_set(&dev->lost_pixels, 1);
1927                pr_warn("wait for urb interrupted: %x available: %d\n",
1928                       ret, dev->urbs.available);
1929                goto error;
1930        }
1931
1932        spin_lock_irqsave(&dev->urbs.lock, flags);
1933
1934        BUG_ON(list_empty(&dev->urbs.list)); /* reserved one with limit_sem */
1935        entry = dev->urbs.list.next;
1936        list_del_init(entry);
1937        dev->urbs.available--;
1938
1939        spin_unlock_irqrestore(&dev->urbs.lock, flags);
1940
1941        unode = list_entry(entry, struct urb_node, entry);
1942        urb = unode->urb;
1943
1944error:
1945        return urb;
1946}
1947
1948static int dlfb_submit_urb(struct dlfb_data *dev, struct urb *urb, size_t len)
1949{
1950        int ret;
1951
1952        BUG_ON(len > dev->urbs.size);
1953
1954        urb->transfer_buffer_length = len; /* set to actual payload len */
1955        ret = usb_submit_urb(urb, GFP_KERNEL);
1956        if (ret) {
1957                dlfb_urb_completion(urb); /* because no one else will */
1958                atomic_set(&dev->lost_pixels, 1);
1959                pr_err("usb_submit_urb error %x\n", ret);
1960        }
1961        return ret;
1962}
1963
1964module_param(console, bool, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP);
1965MODULE_PARM_DESC(console, "Allow fbcon to open framebuffer");
1966
1967module_param(fb_defio, bool, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP);
1968MODULE_PARM_DESC(fb_defio, "Page fault detection of mmap writes");
1969
1970module_param(shadow, bool, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP);
1971MODULE_PARM_DESC(shadow, "Shadow vid mem. Disable to save mem but lose perf");
1972
1973module_param(pixel_limit, int, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP);
1974MODULE_PARM_DESC(pixel_limit, "Force limit on max mode (in x*y pixels)");
1975
1976MODULE_AUTHOR("Roberto De Ioris <roberto@unbit.it>, "
1977              "Jaya Kumar <jayakumar.lkml@gmail.com>, "
1978              "Bernie Thompson <bernie@plugable.com>");
1979MODULE_DESCRIPTION("DisplayLink kernel framebuffer driver");
1980MODULE_LICENSE("GPL");
1981
1982
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