Nov 5, 2023

Force Enable VRR using EDID

My Samsung LC24RG50 supports FreeSync, but it wouldn’t play nice with my Intel ARC GPU, so I ended up force enabling it in the EDID.

Modifying the EDID

After a bunch of troubleshooting, I did end up making my monitor present a VRR EDID, which I dumped here, but here’s the things you should modify if you can’t:

1. Acquire your monitor’s EDID, I used get-edid > monitor.bin
2. Using wxEDID, view the EDID’s MRL section
3. Set extd_timg to 0x01, I believe this is required for VRR
4. Make sure min_Vfreq and max_Vfreq are correctly set to your monitor’s range (eg. 48-144 Hz)
5. I’m not sure but I think min_Hfreq should be the same as max_Hfreq, if it’s not set it to the same as max_Hfreq (eg. Both 168 kHz)

Applying the EDID (on Wayland)

1. Copy the EDID to /usr/lib/firmware/edid/
2. Add drm.edid_firmware=DP-1:edid/monitor.bin to your kernel command line, replacing DP-1 with your monitor’s connector name, and monitor.bin with the EDID file name.
3. You may need to create an initramfs hook script, I used this one.
4. Reboot

Multiple EDIDs

You can specify multiple EDIDs in the kernel command line using a comma, eg. drm.edid_firmware=DP-1:edid/monitor1.bin,DP-2:edid/monitor2.bin

Thanks for reading!
Steve.

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