Bug 35607 - glXWaitVideoSyncSGI() function freezes at resolution change
Summary: glXWaitVideoSyncSGI() function freezes at resolution change
Alias: None
Product: Mesa
Classification: Unclassified
Component: GLX (show other bugs)
Version: git
Hardware: All Linux (All)
: medium normal
Assignee: mesa-dev
QA Contact:
Depends on:
Reported: 2011-03-23 15:43 UTC by alanw
Modified: 2019-09-18 17:43 UTC (History)
1 user (show)

See Also:
i915 platform:
i915 features:


Description alanw 2011-03-23 15:43:16 UTC
I am testing some recent Intel platforms like Ironlake and Sandy Bridge. With the multiplatform XBMC Media Center software i realized a bug probably in mesa drivers. 

The movie player adjusts the refresh rate of the resolution while watching a movie to match the film fps the best. The problem is that if we use this function the program hangs. It doesn't not hang when i don't change refresh rate or i don't have vblank syncronization on. This refresh rate change function perfectly works with Nvidia hardware and drivers. Also it works with Intel hw but the windows build of this software.

Consulting with the developers and using gdb debugging we found out that the reason of the hang is that the call glXWaitVideoSyncSGI() hangs in case there is a resolution change happened.

There is another scenario when this function fails. When i am in GUI menu and checking the actual framerate (with vblank on) it shows the good framerate, until i start changing to the virtual terminals with ctrl+f2 and than back to Xorg screen. If the refresh rate of KMS differs from the refresh rate i set in xorg.conf, strangely the framerate starts going up maxed at ca. 120. Just like if i turn on sync to vblank completely. So i loose vblank sync again.

It would be really good to fix this, so that a lot of Media Center users can have a full experience with mesa and Intel hardware.

dmesg: http://pastebin.com/3mSLmZUt
xorg.log http://pastebin.com/3jeHmMr2

Ubuntu Natty, Kernel 2.6.38
Comment 1 Eero Tamminen 2016-09-12 14:27:05 UTC
Alan, this sounds more like X bug than Mesa one.  Is it still reproducible?
Comment 2 GitLab Migration User 2019-09-18 17:43:41 UTC
-- GitLab Migration Automatic Message --

This bug has been migrated to freedesktop.org's GitLab instance and has been closed from further activity.

You can subscribe and participate further through the new bug through this link to our GitLab instance: https://gitlab.freedesktop.org/mesa/mesa/issues/75.

Use of freedesktop.org services, including Bugzilla, is subject to our Code of Conduct. How we collect and use information is described in our Privacy Policy.