Custom EDID

EDID (Extended Display Identification Data) is metadata provided by a display to the operating system, to inform the later about supported resolutions, refresh rates, etc. It also provides defaults or recommendations for those values.

Some displays provide wrong EDID, resulting in bad default resolutions and refresh rates, as well as issues such as GPU memory clock being stuck resulting in enormous power draw during idle. This happens due to the driver not having time to clock down without causing flickering, due to wrong blank timing provided by EDID.

Additionally, modifying the EDID allows having the desired resolution and refresh rate set by deault in most programs, which usually take the default suggested by EDID, that is more often than not less than the display is capable of.

For those reasons it is very useful to load custom EDID.

How to use custom EDID

• Get the default EDID:
  The default EDID can be read from /sys/class/drm/@GPU@-@DISPLAY@/edid, e.g. cat /sys/class/drm/card0-DP-1/edid > default.bin.
• Edit the EDID:
  Use an editor of choice to edit the EDID, AW EDID Editor works very well through wine.
• Optionally test the new EDID:
  For this the debugfs can be used at sys/kernel/debug/dri/@GPUNUM@/@DISPLAY@/edid_override e.g. cat @NEWEDIDFILE > sys/kernel/debug/dri/0/DP-1/edid_override. Then replug the monitor and check if it worked.
• Automatically apply the EDID during boot:
  • copy the custom EDID to /lib/firmware/edid/@FILE@, e.g. /lib/firmware/edid/DP-1.bin.
  • Instruct the Kernel to load said EDID by adding drm.edid_firmware=@DISPLAY@:edid/@FILE@,@DISPLAY2@:edid/@FILE2@, e.g. drm.edid_firmware=DP-1:edid/DP-1.bin,DP-2:edid/DP-2.bin. This can be done before compilation in make menuconfig at Processor type and features -> Built-in kernel command line or in the bootloader settings.

See also

• Fix AMD GPU high idle power MCLK (using a different EDID editor)