Black screens on A10-8780P (Carrizo) + R7 M260/M265 (Topaz) Combo
Submitted by Thomas J. Moore
Assigned to Default DRI bug account
Created attachment 125267
dmesg from my latest boot (with some wifi messages at end deleted for privacy)
I have an HP Pavilion 17-g133cl with A10 Carrizo+Topaz. I struggled for hours/days to get this to actually display anything at all using the amdgpu driver. In the mean time, efifb works perfectly every time (except of course no 3d, no X resolution switching, no brightness control, and slow enough that video playing is also impossible). Since it seemed like there were just issues powering up the display controller correctly, I decided at first to add my notes to https://bugzilla.kernel.org/show_bug.cgi?id=117591 but my symptoms (and cures) are, indeed, different. After much blind playing with my system (I have no way to ssh in, and the keyboard is flaky as well, so that was a lot of fun), I made the following observations:
- kernel power management options appeared to have no effect
- sometimes (very rarely), it just starts working, regardless
- once it starts working for more than 1 minute, it stays working
- often, it starts partially working, by giving me a flickering display
- often, it starts working with a stable display, only to start flickering again after a few seconds (very rarely even going completely black gain)
- my first way of fixing it is fairly reliable, but almost always requires at least one blind reboot before it starts giving my a display: xrandr --output eDP --crtc 1 (added to my .xinitrc)
- if, when it finally comes up, it is flickering, it can be cured by toggling the crtc between 0 and 1 often enough until it remains stable for at least a minute.
- if crtc 1 is enabled when X is killed, the machine goes blank and hangs hard; switching consoles while X is up works, though (although the consoles remain black).
- changing the crtc to 1 in X does nothing for the console; only X displays anything. I have not tried to write a libdrm program to make the console switch to crtc 1, nor have I managed to trace where the crtc list comes from, or how to force it in the amdgpu driver itself.
- if, instead of playing with the crtc, I play with power management again, I seem to be able to get it working by booting once with power management enabled, then rebooting with it disabled, and then it works (video in console as well as X, and no crtc switching necessary). However, that may just have been how it decides to work today, and tomorrow it will no longer work.
I get identical behavior with kernels 4.6.2, 4.6.3, 4.6.4, 4.7-rc4 (which I decided to try given the supposed major amdgpu overhaul), 4.4.15 (which I decided to try given that the poster of the kernel.org bug was using Ubuntu's 4.4 kernel) (all on Gentoo; with the exception of 4.7-rc4, this is with Gentoo's fbdecor patches, but I obviously have that disabled while working through this problem).
Overall, this is very weird and frustrating. I've had power management issues with previous Radeon laptops (all of them), but the gpu pm issue usually manifested as hard locks while playing games with power management enabled, not this crap. I have a feeling that anything that gets it to work only gets it to work due to random chance, and it's just that I'm beating at it often enough that I finally hit the jackpot at some point, and it keeps working correctly until I power cycle for an extended period again. I also get the feeling that I must be a major masochist to keep using ATI/AMD hardware, given that in 15+ years of using it I've never had an experience better than "meh, mostly works". If I weren't dead broke, I'd have chucked this machine over a freeway overpass and bought something else.
**Attachment 125267**, "dmesg from my latest boot (with some wifi messages at end deleted for privacy)":