amdgpu does not support 3840x2160@30Hz on kaveri apu
Brief summary of the problem:
Davide Corrado davide@davidecorrado.eu
hello, I'd like to report this issue that I am having since I updated my display (samsung U28E590). The amdgpu does not support the native resolution of my new monitor, which is 3840x2160. Using a HDMI or DVI connection (I tried both, same result), the maximum supported refresh is 30Hz, so I'm stuck with that (don't have a displayport). The radeon module works fine, I'm having this issue just when I use amdgpu (which I'd like to use, because performance is better).
please note also: If I boot the system using amdgpu and no video mode selection, the system boots but I don't get a screen during boot and in wayland. I can connect using ssh, so the system is running fine, just no display; If I force a full HD resolution with "video:" in the kernel line, I can see the boot process but the screen disappears when wayland starts (because the default resolution is 3840x2160@30Hz). Using a full HD monitor results in no issues, so it must be related to this very 4k resolution.
Hardware description:
amd A10 7870k APU Display: samsung U28E590 connected via HDMI or DVI Distro: fedora 33 (tried ubuntu 20.04, same result) kernel: 5.9.16-200.fc33.x86_64 #1 (closed) SMP Mon Dec 21 14:08:22 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
How to reproduce the issue:
switch to amdgpu while connected to my monitor (or maybe just a monitor that supports 3840x2160@30Hz)
Attached files:
I attach lspci -nn (file hw.txt)hw.txt
dmesg and journactl -ab with radeon and the same files with amdgpu enabled