[Mesa-dev] [Bug 35607] New: glXWaitVideoSyncSGI() function freezes at resolution change

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=35607

           Summary: glXWaitVideoSyncSGI() function freezes at resolution
                    change
           Product: Mesa
           Version: git
          Platform: All
        OS/Version: Linux (All)
            Status: NEW
          Severity: normal
          Priority: medium
         Component: GLX
        AssignedTo: mesa-dev at lists.freedesktop.org
        ReportedBy: alanwww1 at gmail.com


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

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