Bug 195743

Summary:	Screen flicker and instability on hdmi monitors with AMDGPU, EDID problems
Product:	Drivers	Reporter:	keziolio123
Component:	Video(DRI - non Intel)	Assignee:	drivers_video-dri
Status:	RESOLVED INVALID
Severity:	high
Priority:	P1
Hardware:	All
OS:	Linux
Kernel Version:	4.10.13	Subsystem:
Regression:	No	Bisected commit-id:
Attachments:	dmesg output with the problem, and an xrandr segfault

Description keziolio123 2017-05-13 10:44:29 UTC

Hi, I want to report the bug described in this forum thread: https://www.phoronix.com/forums/forum/linux-graphics-x-org-drivers/open-source-amd-linux/947352-recent-extremely-annoying-multimonitor-bug-don-t-know-where-to-report

I'll copy the relevant part for convenience:

"basically it acts like monitors are unplugged and plugged back in, and often the detected EDID is wrong, like dmesg suggests, wrong resolutions are found and I remain with one monitor right, one in 1024*768 and the other one off, not even detected.
This happens only with HDMI monitors, the one DVI monitor that I have seems to always work reliably, and swapping them has no effect, the left one seems to have always the same problems (wrong resolution).

In the video, the center monitor is DVI, the other two are identical, connected with hdmi and are affected by the problem.


I'm 100% sure everything was working right until some weeks ago, never had any issues with xonotic or cheese in years, i've reproduced also with serious sam fusion beta

GPU is a sapphire RX480"

Here's a youtube video of the problem: https://www.youtube.com/watch?v=Tfu_pxRVHag

The system now is basically unusable with multiple monitors and 3d apps, with continuous flicker

Comment 1 keziolio123 2017-05-13 10:49:13 UTC

Created attachment 256503 [details]
dmesg output with the problem, and an xrandr segfault

Comment 2 Michel Dänzer 2017-05-15 09:03:54 UTC

Did you update to a newer kernel version when the problem started, or what changed?

Comment 3 keziolio123 2017-05-16 14:13:30 UTC

Thanks for the reply 

Yes I did update the kernel, along with the rest of the system (I use ArchLinux).

The problem seems to be getting worse, from linux 4.7 to 4.10 and git, with latter versions the "screens off and on" flicker seems to be cycling and generally more unstable (on 4.10), instead of an "one shot" glitch that I can fix with xrandr (on 4.7). This is why I think it's a kernel issue.

Unfortunately for now I can't easily bisect the kernel version, as I use btrfs and it breaks if I load an old kernel. I'll try later with a live system but that's going to take some time.

I have 3 monitors, two of them HDMI and one DVI, only the HDMI ones are affected, even if I found breakage on the DVI one some times.


The problem does not occur in wayland, only xorg is affected. But I tried older versions of xorg and the problem persists (so I guess it's not a xorg issue)

I tried to force the edid with the kernel command line, but the problem still occurs, the monitors do shut down (they are not detected) or flicker

I don't really know what to try now, and I have not found a workaround yet, disabling udev has no effect.

Comment 4 keziolio123 2017-05-22 19:06:19 UTC

That was probably an hardware issue, closing