Bug 1079899 - 4.15 AMD DC not ready for mainstream but enabled by default - causes flickering and backtraces in dmesg
4.15 AMD DC not ready for mainstream but enabled by default - causes flickeri...
Status: RESOLVED UPSTREAM
Classification: openSUSE
Product: openSUSE Tumbleweed
Classification: openSUSE
Component: Kernel
Current
Other Other
: P5 - None : Normal (vote)
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Reported: 2018-02-07 17:26 UTC by Jon Brightwell
Modified: 2018-06-16 12:14 UTC (History)
3 users (show)

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jslaby: needinfo? (jon)


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Description Jon Brightwell 2018-02-07 17:26:57 UTC
Kernel bug report
https://bugzilla.kernel.org/show_bug.cgi?id=198713

I recommend turning off CONFIG_DRM_AMD_DC_PRE_VEGA. It is EXPERIMENTAL and currently broken for some pre-vega cards (issues reported on 4x0 and fury), causing flickering and traces in dmesg (see kernel bug report for the dozen in one boot).
Flickering is present in KDE OGL3 compositor when UI is updated and randomly per monitor about once every 10s.

It has to be manually disabled with amdgpu.dc=0, and it fixes all issues. Why is an unrecommended experimental on by default?

Those that want to try HDMI audio and freesync can always do amdgpu.dc=1 if they don't have a vega.
Comment 1 Michael Zapf 2018-02-08 13:43:39 UTC
I was pretty happy to finally see HDMI audio output again (having a DolbyD receiver with speakers) ... but after the recent updates, when I turn off my monitor or it goes into power-save, the screen resolution is reset to 1368x768, messing up the whole desktop.

If I turn the DC off I'll have to reconfigure my audio again...
Comment 2 Jiri Slaby 2018-02-13 09:52:11 UTC
(In reply to Jon Brightwell from comment #0)
> It has to be manually disabled with amdgpu.dc=0, and it fixes all issues.
> Why is an unrecommended experimental on by default?

The config is not marked as EXPERIMENTAL. Where did you get this info from?
Comment 3 Jon Brightwell 2018-02-13 10:03:48 UTC
(In reply to Jiri Slaby from comment #2)
> (In reply to Jon Brightwell from comment #0)
> > It has to be manually disabled with amdgpu.dc=0, and it fixes all issues.
> > Why is an unrecommended experimental on by default?
> 
> The config is not marked as EXPERIMENTAL. Where did you get this info from?

Sorry, my bad. I was under the impress pre_vega was experimental, but it looks like they just jumped right in, crashes and all. I guess nothing to do here for oS as the traces have been reported upstream and I've received no further complains from others on reddit or discord.
Comment 4 Jiri Slaby 2018-06-16 12:14:12 UTC
ok, thanks.