R9 290 sets a graphic mode it can't manage, causing black screen
Brief summary of the problem:
R9 290 sets a graphhic mode it can't manage, causing black screen
Hardware description:
- CPU: FX-8350
- GPU: R9 290
- System Memory: 8GB
- Display(s): Lenovo Thinkvision P44W-10
- Type of Diplay Connection: DP
System information:
- Distro name and Version: Manajaro current
- Kernel version: 5.7.9
How to reproduce the issue:
My system boots directly from grub to X greeter. I got a blank screen after grub. After forcing a videomode in the kernel boot params and going to a text console, I detected the problem was the GPU use setting a graphic mode (3840x1200 at 144hz) it cannot use (DP 1.2 can't manage that resolution at that frame rate, max is 120 Hz) . I limited the refresh rate to 120Hz on /usr/share/X11/xorg.conf.d/10-amdgpu.conf :
Section "Monitor" Identifier "DisplayPort-0" HorizSync 30.0 - 178.0 VertRefresh 24.0 - 120.0 EndSection
This solved the problem.
I attach two Xorg log files, in Xorg.1.log you have a boot before adding the Monitor section (blank screen). This is the line in that log for the 144hz mode:
[ 595.102] (II) AMDGPU(0): Modeline "3840x1200"x144.0 718.47 3840 3908 3940 4040 1200 1208 1214 1235 -hsync -vsync (177.8 kHz eP)
I'm not sure what files are needed to debug this issue, so please point me to what you need for a proper diagnostic.