Bug 104655

Summary:

AMD R9 Fury + BenQ XL2546: Setting 240 Hz results in screen distortion

Product:

DRI

Reporter:

ominous

Component:

DRM/AMDgpu

Assignee:

Default DRI bug account <dri-devel>

Status:

RESOLVED FIXED

QA Contact:

Severity:

normal

Priority:

medium

Version:

unspecified

Hardware:

x86-64 (AMD64)

OS:

Linux (All)

Whiteboard:

i915 platform:

i915 features:

Attachments:

Description	Flags
240 Hz right side screen distortion picture	none
240 Hz right side screen distortion video	none
dmesg	none

Description ominous 2018-01-16 12:43:46 UTC

I recently obtained this monitor and running it on Debian via an AMD R9 Fury.

When I try to set the monitor at 1920 x 1080 @ 240 Hz it will show distortion on the right side of the screen, and the screen reports to be running at 1920 x 1080 @ 241 Hz via the Information section of the monitor's OSD.

This does not happen on Windows. I have tested this on Debian stable, Debian testing and Ubuntu 17.10, with all expressing the same result.

The value is 239.76, yet when I switch to it, the monitor will report 241 Hz, which most likely causes the screen distortion.

user@fdt:~$ xrandr
Screen 0: minimum 320 x 200, current 1920 x 1080, maximum 16384 x 16384
DisplayPort-0 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 544mm x 303mm
   1920x1080     60.00 + 239.76   143.98*  119.98    99.93    50.00    59.94  
   1920x1080i    60.00    50.00    59.94  
   1680x1050     59.95  
   1600x900      60.00  
   1280x1024    239.77   120.05    75.02    60.02  
   1280x800      59.81  
   1152x864      75.00  
   1280x720      60.00    50.00    59.94  
   1024x768      75.03    60.00  
   832x624       74.55  
   800x600       75.00    60.32  
   720x576       50.00  
   720x480       60.00    59.94  
   640x480       75.00    60.00    59.94  
   720x400       70.08  
DisplayPort-1 disconnected (normal left inverted right x axis y axis)
DisplayPort-2 disconnected (normal left inverted right x axis y axis)
HDMI-A-0 disconnected (normal left inverted right x axis y axis)
DVI-D-0 disconnected (normal left inverted right x axis y axis)

Comment 1 ominous 2018-01-17 09:13:19 UTC

Created attachment 136802 [details]
240 Hz right side screen distortion picture

Comment 2 ominous 2018-01-17 09:13:49 UTC

Created attachment 136803 [details]
240 Hz right side screen distortion video

Comment 3 Nicolai Hähnle 2018-01-17 11:23:04 UTC

This is probably a display driver bug, not a Mesa bug.

Please provide your kernel version and dmesg output.

Comment 4 ominous 2018-01-17 11:41:29 UTC

Created attachment 136806 [details]
dmesg

Comment 5 ominous 2018-01-20 06:05:17 UTC

I have installed Ubuntu 16.04 so I could try this with AMDGPU-PRO. The 240 Hz distortion still occurs.

Comment 6 ominous 2018-01-21 15:09:27 UTC

Tested this with my on-board Intel graphics capabilities.

The issue does not occur. It seems to be isolated to AMD graphics.

Comment 7 ominous 2018-01-22 21:52:50 UTC

With the help of hwentlan @ irc.freenode.net #radeon I was able to obtain a solution.

Using kernel 4.15 RC9 on Ubuntu 16.04 and booting with the amdgpu.dc=1 kernel option, the issue no longer occurs.

This toggle indicates the use of the new amdgpu driver. So one can assume that this is fixed as of 4.15 and when that toggle becomes standard.

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