Nouveau - Dec 2007 - [Bug 13866] New: RandR 1.2 gives Xvideo tearing

http://bugs.freedesktop.org/show_bug.cgi?id=13866

           Summary: RandR 1.2 gives Xvideo tearing
           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


Enabling RandR 1.2 gives me a lot of video tearing on my Geforce 7300 GT. It
doesn't matter if two outputs are enabled or not, simply using the new RandR
1.2 stuff produces the problem.


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drzeus-bugzilla at drzeus.cx changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|RandR 1.2 gives Xvideo      |nouveau gives Xvideo tearing
                   |tearing                     |




------- Comment #1 from drzeus-bugzilla at drzeus.cx  2008-01-03 12:57 PST
-------
I've tested things a bit further. RandR 1.2 is not needed to produce the
problem, but having two output enabled worsens the problem.

Things work fine with the nv driver, so you do not need to compare with the
closed one.

I've confirmed that all three test cases (nv, nouveau "normal",
nouveau
"randr") use the same mode line. The RandR code path selects a
different one by
default, but I switched it to get a valid comparison.

This card does not have any overlay, so it's the blitter that's
involved.


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------- Comment #2 from madman2003 at gmail.com  2008-01-03 14:57 PST -------
I think you're using the texture adapter, which doesn't have sync to
vblank yet
(it still has to be reverse engineered). But can you confirm that the tearing
is diaginal? And that xvinfo shows the texture adapter first?


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------- Comment #3 from drzeus-bugzilla at drzeus.cx  2008-01-03 22:32 PST
-------
The tearing is horisontal, not diagonal. But the texture adaptor is indeed
first in xvinfo.

But I believe I'm using the blitter. The driver does syncing, it just fails
ever so slightly. :)

If I disable XV_SYNC_TO_VBLANK, things go south really badly. Keeping it on, it
is almost in sync but with constant, slight glitches. I've been trying to
put
together a simple test case but it has proven to be very difficult. So far I
can only reproduce it consistently with mplayer.


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------- Comment #4 from drzeus-bugzilla at drzeus.cx  2008-01-05 01:55 PST
-------
Ah, I see what is happening now, and you were right.

mplayer, where I'm seeing the tearing, uses the first port found. But my
tests
were using the last port. So one used the texture adapter, and one the blitter.
If I change my tests to use the texture adapter, the problem is apparent. It
also explains why nv works as it doesn't have the texture adapter.

So I have a couple of questions:

1. What's the difference between the two? Judging from the names I'd
guess the
texture adapter uses the 3D engine and the blitter the 2D engine.

2. Why two? I.e. why is the blitter insufficient?

3. Why is the texture adapter the first (and therefore picked by programs) if
it is inferior to the blitter when it comes to displaying video?

4. Why does vsync need rev.eng.? I tested adding a simple
FIRE_RING()/NVWaitVSync() and it removed the tearing.


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------- Comment #5 from madman2003 at gmail.com  2008-01-05 03:27 PST -------
1. Indeed.
2. The blitter doesn't support YV12 which is a very common color space.
3. It gives people reason to improve it ;-) (also defaults get better feedback)
4. This does not work well for me and many others. It is believed that the 3d
engine has it's own sync.


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------- Comment #6 from drzeus-bugzilla at drzeus.cx  2008-01-05 11:30 PST
-------
For the time being, could we get an config option that reverses the order of
the ports? Or disables the texture adapter? :)


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--- Comment #7 from Arthur Huillet <arthur.huillet at free.Fr>  2008-01-20
06:32:40 PST ---
Hello,

is this still an issue?


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--- Comment #8 from Maarten Maathuis <madman2003 at gmail.com>  2008-01-20
08:17:54 PST ---
Can you please retry with current git. Please keep in mind that the composited
case may not be perfect, but it should improve.


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--- Comment #9 from Maarten Maathuis <madman2003 at gmail.com>  2008-01-20
10:08:30 PST ---
I removed the potentionally problematic workaround for composite situations,
please make sure you try without composite.


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Pierre Ossman <drzeus-bugzilla at drzeus.cx> changed:

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




--- Comment #10 from Pierre Ossman <drzeus-bugzilla at drzeus.cx> 
2008-01-20 10:40:58 PST ---
The latest additions correctly vsyncs for the texture adapter on both CRTCs
here. Closing bug.


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