linux/Documentation/fb/metronomefb.rst
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   1===========
   2Metronomefb
   3===========
   4
   5Maintained by Jaya Kumar <jayakumar.lkml.gmail.com>
   6
   7Last revised: Mar 10, 2008
   8
   9Metronomefb is a driver for the Metronome display controller. The controller
  10is from E-Ink Corporation. It is intended to be used to drive the E-Ink
  11Vizplex display media. E-Ink hosts some details of this controller and the
  12display media here http://www.e-ink.com/products/matrix/metronome.html .
  13
  14Metronome is interfaced to the host CPU through the AMLCD interface. The
  15host CPU generates the control information and the image in a framebuffer
  16which is then delivered to the AMLCD interface by a host specific method.
  17The display and error status are each pulled through individual GPIOs.
  18
  19Metronomefb is platform independent and depends on a board specific driver
  20to do all physical IO work. Currently, an example is implemented for the
  21PXA board used in the AM-200 EPD devkit. This example is am200epd.c
  22
  23Metronomefb requires waveform information which is delivered via the AMLCD
  24interface to the metronome controller. The waveform information is expected to
  25be delivered from userspace via the firmware class interface. The waveform file
  26can be compressed as long as your udev or hotplug script is aware of the need
  27to uncompress it before delivering it. metronomefb will ask for metronome.wbf
  28which would typically go into /lib/firmware/metronome.wbf depending on your
  29udev/hotplug setup. I have only tested with a single waveform file which was
  30originally labeled 23P01201_60_WT0107_MTC. I do not know what it stands for.
  31Caution should be exercised when manipulating the waveform as there may be
  32a possibility that it could have some permanent effects on the display media.
  33I neither have access to nor know exactly what the waveform does in terms of
  34the physical media.
  35
  36Metronomefb uses the deferred IO interface so that it can provide a memory
  37mappable frame buffer. It has been tested with tinyx (Xfbdev). It is known
  38to work at this time with xeyes, xclock, xloadimage, xpdf.
  39