Arch Linux

889664

Member

Registered: 2022-05-04

Posts: 6

[Solved] Screen Resolution only 640x480

Greetings, everyone.

Recently my desktop (amd 5700G) has had a strange problem that the screen resolution stuck at 640x480  both in virtual console and X window mode (DP and HDMI), but the resolution is well in grub.

Precisely speaking (please watch the screenshots, if you're confused),
when in virtual console, only top-left corner is usable (640x480 out of 2560x1440), but if I play a video with mpv, all screen area is usable at full-screen;
https://imgur.com/a/fkfcO9c

when in X window, the resolution default to 640x480, while the results of xrandr looks fine, but if I change the resolution with

$ xrandr --output DisplayPort-0 --mode 2560x1440

Then the result is just like virtual console: the resolution is ok, but only top-left corner is usable.
https://imgur.com/a/C5xZX3K

I've noticed some "error" in dmesg:
[    2.012156] [drm:dc_link_detect_helper [amdgpu]] *ERROR* No EDID read.
Full dmesg is here.https://pastebin.com/0t0PMFrN

Here are some basic information and what have been done.

$ uname -r
5.15.37-1-lts

$  lspci -v | grep -e 3D -e VGA
04:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Cezanne (rev c8) (prog-if 00 [VGA controller])

Full lspci results is here.https://pastebin.com/kEvAfvft

#  hwinfo --framebuffer
02: None 00.0: 11001 VESA Framebuffer                           
  [Created at bios.459]
  Unique ID: rdCR.IqA6stF5CC9
  Hardware Class: framebuffer
  Model: "(C) 1988-2018, Advanced Micro Devices RENOIR"
  Vendor: "(C) 1988-2018, Advanced Micro Devices, Inc."
  Device: "RENOIR"
  SubVendor: "AMD ATOMBIOS"
  SubDevice: 
  Revision: "01.00"
  Memory Size: 48 MB
  Memory Range: 0x00000000-0x02ffffff (rw)
  Config Status: cfg=new, avail=yes, need=no, active=unknown

Strangely, there are no "mode" in the output above.

I've tried modify lines in /etc/default/grub

GRUB_GFXMODE=2560x1440x32

and (re)installed latest linux(-lts) kernel, linux-firmware, xf86-video-amdgpu, xorg, and grub, but to no avail so far.

Oh, additionally,
1. I booted the desktop with LiveCDs (both Ubuntu 20.04 and 2022-04 Arch Linux) and the screen is fine.
2. The screen resolution will be fixed by the following command in virtual console temporarily, but since it's a desktop, X Window is necessary:

# fbset -xres 2560 -yres 1440

Thank you.

Dirty Solution:
Unplug my decades old 2nd monitor fixed the problem.

After months of idling my desktop, I by chance realised the second monitor might be the culprit, so I unplugged it, then the main monitor is fine.
The real cause of the problem is beyond my knowledge, but I suspect it is a bug of Arch Linux's configuration, because everything was fine until a -Syu update around April 10th, and the screen is fine with other distributions of Linux.

Last edited by 889664 (2022-08-08 01:51:09)