Bug 109359 - Flickering and artifacts on dual 4K displays from RX 570
Summary: Flickering and artifacts on dual 4K displays from RX 570
Status: NEW
Alias: None
Product: DRI
Classification: Unclassified
Component: DRM/AMDgpu (show other bugs)
Version: unspecified
Hardware: x86-64 (AMD64) Linux (All)
: medium normal
Assignee: Default DRI bug account
QA Contact:
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Reported: 2019-01-14 21:21 UTC by Timur Kristóf
Modified: 2019-01-31 17:06 UTC (History)
3 users (show)

See Also:
i915 platform:
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Attachments
dmesg log (92.19 KB, text/plain)
2019-01-15 14:26 UTC, Timur Kristóf
no flags Details
xorg log (55.30 KB, text/x-log)
2019-01-15 14:28 UTC, Timur Kristóf
no flags Details

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Description Timur Kristóf 2019-01-14 21:21:45 UTC
There are two Dell U2718Q 4K monitors connected to a Sapphire Pulse RX 570 ITX card, one using the DisplayPort output and the other using the HDMI output.

There is a visible flickering artifact on both displays. There is no problem when only a single display is connected.

Searching online yields a couple of results that suggest a workaround: manually increasing the shader and/or memory clock of the GPU. On the RX 570 the following commands can get rid of the problem:

echo "manual" > /sys/class/drm/card0/device/power_dpm_force_performance_level
echo "2" > /sys/class/drm/card0/device/pp_dpm_mclk
echo "5 6 7" > /sys/class/drm/card0/device/pp_dpm_sclk

However, I believe the amdgpu driver should be able to figure out the correct necessary clock settings on its own. The problem exists in Linux 4.19 and 5.0-rc1 as well.
Comment 1 Alex Deucher 2019-01-14 21:38:02 UTC
Please attach your dmesg output and xorg log (if using X).
Comment 2 Timur Kristóf 2019-01-15 14:26:50 UTC
Created attachment 143126 [details]
dmesg log
Comment 3 Timur Kristóf 2019-01-15 14:28:12 UTC
Created attachment 143127 [details]
xorg log
Comment 4 keziolio123 2019-01-22 21:31:06 UTC
I have the same issue with an RX480 if i set amdgpu.ppfeaturemask=0xffffffff (for overclocking), without any command line changes there is no flickering
Comment 5 Timur Kristóf 2019-01-22 23:04:00 UTC
(In reply to keziolio123 from comment #4)
> I have the same issue with an RX480 if i set amdgpu.ppfeaturemask=0xffffffff
> (for overclocking), without any command line changes there is no flickering

That's because when you overclock, your clock speed gets high enough so that flickering doesn't happen.


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