Bug 109392 - modesetting driver + amdgpu.dc=1 always enforces vsync
Summary: modesetting driver + amdgpu.dc=1 always enforces vsync
Status: RESOLVED NOTOURBUG
Alias: None
Product: xorg
Classification: Unclassified
Component: Driver/AMDgpu (show other bugs)
Version: git
Hardware: x86-64 (AMD64) Linux (All)
: medium normal
Assignee: xf86-video-ati maintainers
QA Contact: Xorg Project Team
URL:
Whiteboard:
Keywords:
Depends on:
Blocks:
 
Reported: 2019-01-19 13:02 UTC by tempel.julian
Modified: 2019-01-21 11:32 UTC (History)
0 users

See Also:
i915 platform:
i915 features:


Attachments
dmesg log (66.64 KB, text/x-log)
2019-01-19 13:02 UTC, tempel.julian
no flags Details
xorg log (51.11 KB, text/plain)
2019-01-19 13:02 UTC, tempel.julian
no flags Details

Description tempel.julian 2019-01-19 13:02:03 UTC
Created attachment 143158 [details]
dmesg log

When amdgpu.dc=1 and modesetting driver are used at the same time, fps in 3D applications can't exceed monitor refreshrate and there is always no tearing, despite of vsync enabled or not in the applications.
Happens with both radeonsi and radv. For OGL apps, forcing vsync off via vblank_mode=0 also doesn't show any effect in this case.

The issue doesn't occur with amdgpu.dc=0 + modesetting or with xf86-video-amdgpu.

Though I think having an option for globally enforcing vsync would be tempting if an application doesn't offer vsync for whatever reasons. radv and amdvlk also don't offer options to enforce vsync, just radeonsi does.
Perhaps it could be a sub-option for TearFree?

linux drm-next-5.1-wip 5acc93145bf97a0d59ee65255cae8e1bd0623b07
xorg-server 1.20.3
Comment 1 tempel.julian 2019-01-19 13:02:19 UTC
Created attachment 143159 [details]
xorg log
Comment 2 Michel Dänzer 2019-01-21 11:32:04 UTC
modesetting driver bugs need to be reported at https://gitlab.freedesktop.org/xorg/xserver/issues/new .


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