Nouveau - Jan 2008 - [Bug 13944] New: nouveau video blitter gives tearing with two outputs

http://bugs.freedesktop.org/show_bug.cgi?id=13944

           Summary: nouveau video blitter gives tearing with two outputs
           Product: xorg
           Version: 7.3
          Platform: Other
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: medium
         Component: Driver/nouveau
        AssignedTo: nouveau at lists.freedesktop.org
        ReportedBy: drzeus-bugzilla at drzeus.cx
         QAContact: xorg-team at lists.x.org


When I enable two outputs, the video blitter (not the texture adapter) slightly
mis-syncs so that I have a single tear moving slowly over the screen. Things
work fine as long as only a single output is enabled.


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http://bugs.freedesktop.org/show_bug.cgi?id=13944





------- Comment #1 from drzeus-bugzilla at drzeus.cx  2008-01-06 07:35 PST
-------
The problem is this part of NVWaitVSync():

        /* If crtc1 is active, this will produce one, otherwise zero */
        /* The assumption is that at least one is active */
        OUT_RING  (pNv->crtc_active[1]);

What happens is that it will wait for vsync on CRTC 1 if it's active, and
CRTC
0 otherwise. I assume this was added because bad things happen if you wait for
an inactive CRTC.

This is of course very incorrect in dual-head as it means it will always wait
for CRTC 1. And the vsync of the two CRTCs are unlikely to occur at the same
time.

To fix this, the NVWaitVSync() function needs to wait on the relevant CRTC. But
pScrn seems to be card global, so I guess another parameter needs to be added.
I'm not sure how the callers can determine it either though.


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http://bugs.freedesktop.org/show_bug.cgi?id=13944


Arthur Huillet <arthur.huillet at free.Fr> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED




--- Comment #2 from Arthur Huillet <arthur.huillet at free.Fr>  2008-01-20
06:33:05 PST ---
Closing, since your patch supposedly fixes it.


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