9.3.4.2 Using a Custom Waveform File
To ensure the optimal E Ink display quality, use a waveform file specific to E Ink panel
being used. The raw waveform file type (.wbf) requires conversion to a format that can
be understood and read by the EPDC. This conversion script is not included as part of the
BSP, so please contact Freescale to acquire this conversion script.
Once the waveform conversion script has been run on the raw waveform file, the
converted waveform file should be renamed so that the EPDC driver can find it and load
it. The driver is going to search for a waveform file with the name "imx/
epdc_[panel_name].fw", where panel_name refers to the string specified in the
fb_videomode
name
field. For example, if the panel is named "E60_ABCD", then the
converted waveform file should be named epdc_E60_ABCD.fw.
The firmware script firmware.sh (lib/udev/firmware in the Linux root file system)
contains the search path used to locate the firmware file. The default search path for
firmware files is /lib/firmware;/usr/local/lib/firmware. A custom search path can be
specified by modifying firmware.sh. You’ll need to create an imx directory in one of
these paths and add your new epdc_[panel_name].fw file there.
NOTE
If the EPDC driver is searching for a firmware waveform file
that matches the names of one of the default waveform files
(see preceding chapter), it will choose the default firmware files
that are built into the BSP over any firmware file that has been
added in the firmware search path. Thus, if you leave the BSP
so that it builds those default firmware files into the OS image,
be sure to use a panel name other than those associated with the
default firmware files, since those default waveform files will
be preferred and selected over a new waveform file placed in
the firmware search path.
9.3.5 EPDC Panel Initialization
The framebuffer driver will not typically (see note below for exceptions) go through any
hardware initialization steps when the framebuffer driver module is loaded. Instead, a
subsequent user mode call must be made to request that the driver initialize itself for a
specific EPD panel. To initialize the EPDC hardware and E-ink panel, an
FBIOPUT_VSCREENINFO ioctl call must be made, with the xres and yres fields of the
Software Operation
i.MX 6Solo/6DualLite Linux Reference Manual, Rev. L3.0.35_4.1.0, 09/2013
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Freescale Semiconductor, Inc.
