linux/Documentation/devicetree/bindings/video/display-timing.txt
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   1display-timing bindings
   2=======================
   3
   4display-timings node
   5--------------------
   6
   7required properties:
   8 - none
   9
  10optional properties:
  11 - native-mode: The native mode for the display, in case multiple modes are
  12                provided. When omitted, assume the first node is the native.
  13
  14timing subnode
  15--------------
  16
  17required properties:
  18 - hactive, vactive: display resolution
  19 - hfront-porch, hback-porch, hsync-len: horizontal display timing parameters
  20   in pixels
  21   vfront-porch, vback-porch, vsync-len: vertical display timing parameters in
  22   lines
  23 - clock-frequency: display clock in Hz
  24
  25optional properties:
  26 - hsync-active: hsync pulse is active low/high/ignored
  27 - vsync-active: vsync pulse is active low/high/ignored
  28 - de-active: data-enable pulse is active low/high/ignored
  29 - pixelclk-active: with
  30                        - active high = drive pixel data on rising edge/
  31                                        sample data on falling edge
  32                        - active low  = drive pixel data on falling edge/
  33                                        sample data on rising edge
  34                        - ignored     = ignored
  35 - interlaced (bool): boolean to enable interlaced mode
  36 - doublescan (bool): boolean to enable doublescan mode
  37 - doubleclk (bool): boolean to enable doubleclock mode
  38
  39All the optional properties that are not bool follow the following logic:
  40    <1>: high active
  41    <0>: low active
  42    omitted: not used on hardware
  43
  44There are different ways of describing the capabilities of a display. The
  45devicetree representation corresponds to the one commonly found in datasheets
  46for displays. If a display supports multiple signal timings, the native-mode
  47can be specified.
  48
  49The parameters are defined as:
  50
  51  +----------+-------------------------------------+----------+-------+
  52  |          |        \xE2\x86\x91                            |          |       |
  53  |          |        |vback_porch                 |          |       |
  54  |          |        \xE2\x86\x93                            |          |       |
  55  +----------#######################################----------+-------+
  56  |          #        \xE2\x86\x91                            #          |       |
  57  |          #        |                            #          |       |
  58  |  hback   #        |                            #  hfront  | hsync |
  59  |   porch  #        |       hactive              #  porch   |  len  |
  60  |<-------->#<-------+--------------------------->#<-------->|<----->|
  61  |          #        |                            #          |       |
  62  |          #        |vactive                     #          |       |
  63  |          #        |                            #          |       |
  64  |          #        \xE2\x86\x93                            #          |       |
  65  +----------#######################################----------+-------+
  66  |          |        \xE2\x86\x91                            |          |       |
  67  |          |        |vfront_porch                |          |       |
  68  |          |        \xE2\x86\x93                            |          |       |
  69  +----------+-------------------------------------+----------+-------+
  70  |          |        \xE2\x86\x91                            |          |       |
  71  |          |        |vsync_len                   |          |       |
  72  |          |        \xE2\x86\x93                            |          |       |
  73  +----------+-------------------------------------+----------+-------+
  74
  75Example:
  76
  77        display-timings {
  78                native-mode = <&timing0>;
  79                timing0: 1080p24 {
  80                        /* 1920x1080p24 */
  81                        clock-frequency = <52000000>;
  82                        hactive = <1920>;
  83                        vactive = <1080>;
  84                        hfront-porch = <25>;
  85                        hback-porch = <25>;
  86                        hsync-len = <25>;
  87                        vback-porch = <2>;
  88                        vfront-porch = <2>;
  89                        vsync-len = <2>;
  90                        hsync-active = <1>;
  91                };
  92        };
  93
  94Every required property also supports the use of ranges, so the commonly used
  95datasheet description with minimum, typical and maximum values can be used.
  96
  97Example:
  98
  99        timing1: timing {
 100                /* 1920x1080p24 */
 101                clock-frequency = <148500000>;
 102                hactive = <1920>;
 103                vactive = <1080>;
 104                hsync-len = <0 44 60>;
 105                hfront-porch = <80 88 95>;
 106                hback-porch = <100 148 160>;
 107                vfront-porch = <0 4 6>;
 108                vback-porch = <0 36 50>;
 109                vsync-len = <0 5 6>;
 110        };
 111