Ubuntu assumes an incorrect display size

Bram

12/12/23, 5:48 PM

My display is a 48" AORUS FO48U. This display measures 1052 x 592 mm.

Yet, drm_info will report for the display connector, a size of 700 x 390 mm.

$ drm_info | grep Physical
drmModeGetFB: Invalid argument
│   │   ├───Physical size: 700x390 mm

Note that I drive the display with iGPU of Intel Alderlake.

I am trying to find out where DRM got this incorrect figure from. I am guessing this comes from EDID information.

But read-edid fails to read it for me!

$ sudo get-edid | parse-edid
This is read-edid version 3.0.2. Prepare for some fun.
Attempting to use i2c interface
Problem requesting slave address: Device or resource busy
No EDID on bus 1
No EDID on bus 2
No EDID on bus 3
No EDID on bus 4
No EDID on bus 5
No EDID on bus 6
No EDID on bus 7
No EDID on bus 8
No EDID on bus 9
No EDID on bus 10
No EDID on bus 11
No EDID on bus 12
1 potential busses found: 13
256-byte EDID successfully retrieved from i2c bus 13
Looks like i2c was successful. Have a good day.
You seem to have too many extension blocks. Will not continue to parse
Something strange happened. Please contact the author,
Matthew Kern at <pyrophobicman@gmail.com>

I guess I could email Matthew, but since this is a tool from the 1990s, I doubt he still listens.

How can I get my EDID info? Why does DRM driver think my display is 700mm wide?

OS: Ubuntu 22.10

GPU: UHD Graphics 770 (ADL-S GT1)

Connection: DisplayPort

UPDATE 1

The decode-edid seems to be more capable than read-edid and does manage to parse the EDID:

$ edid-decode /sys/class/drm/card0/card0-DP-1/edid | grep "image size"
    Maximum image size: 70 cm x 39 cm

So EDID reports an incorrect size. Is there a way to override this?

UPDATE 2

Firefox at 100% zoom, with too much white-space:

Firefox at 200% zoom to compensate: messed up layout. NOTE how the words "votes" and "fingerprint" of the 5th question run into each other, for instance.

I want to fix this, but it all starts with the physical size of the display, and then the DPI.

0 + 1

display

dpi

andrew.46

12/12/23, 10:43 PM

Comments are not for extended discussion; this conversation has been [moved to chat](https://chat.stackexchange.com/rooms/141260/discussion-on-question-by-bram-ubuntu-assumes-an-incorrect-display-size).

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: Ubuntu assumes an incorrect display size

Post an answer

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