I got an Acer Aspire A315-41 notebook with AMD Ryzen 5 2500U and i have had problems with brightness not working out of the box (OTB) if i used function buttons. The thing is that i found that it started to work with linux-4.19.37 (fixed) but it didn't work with linux-4.19.35 (broken). It works from 4.19.37 but it doesn't work in later kernel series such as linux-5.0.11 or linux-5.1 and i think the fix should also be in newer kernels. I started to bisect but linux-4.19.36 doesn't boot with my hardware and after many bisect skip and compiling i gave up. Do anyone know what commit that could have fixed it? Or why 4.19.36 won't boot on my hardware (if there was some known regression) so i can perform an bisect.
Can you attach your dmesg outputs for both the working kernels and non-working kernels?
Created attachment 282647 [details] dmesg fixed 4.19.39
Created attachment 282649 [details] dmesg broken 4.19.35
Created attachment 282653 [details] dmesg fixed 4.19.37
By adding commit b59dfdaef173677b0b7e10f375226c0a1114fd20 i was able to boot 4.19.36. I tried 4.19.36 but it was broken. 4.19.36 broken and 4.19.37 fixed. I then ran a bisect but i wasn't able to to find the commit that fixed it. I don't know why the bisect went thru all steps without finding the fix.
The bisect was working i only didn't trust it. What causes the change in behavior wasn't caused by resent fixes, well it was but it wasn't. What makes it work is bumping SUBLEVEL above 36. I tried bumping SUBLEVEL of 5.1 and 5.1.36 was broken while 5.1.37 was working.
Is there anything more i can do to find out what's going on?
Since "echo 100 > /sys/class/backlight/amdgpu_bl0/brightness" works it's not a kernel problem but rather userspace.