Bug 216774

Created attachment 303357 [details]
Single-resolution EDID (1080p120) that demonstrates the problem

The attached EDID is one I've used across multiple operating systems, however on Linux it creates the following additional modes at the DRM level visible with drm_info outside of X/Wayland from the CLI:

1680x1050@120.00
1280x1024@120.00
1440x900@120.00
1280x800@120.00
1280x720@120.00
1024x768@120.00
800x600@120.00
640x480@120.00

This EDID is being loaded via "drm.edid_firmware=eDP:edid.bin" and is present in the initramfs, and this happens both with the stock Ubuntu kernel and when I compiled the latest 5.15.81 kernel from source, so I'm reporting it here.

This might be a misconfiguration or some additional option I need to pass to the drm subsystem to disable some built-in mode-list it's adding by default, or even fixed in later kernel versions and I was simply unaware, if so I apologize for taking up your time!

This EDID is meant to only have a single mode available, 1080p120. Changing the EDID to use 1080p60 (only involves changing the pixel clock value for the single mode and EDID checksum) still has the same problem, and looking at the modes it appears it's just replacing the visible-pixel values with the smaller values and retaining all the other timing details so these seem to be auto-generated somewhere I can't find.