[Bug 43332] New: corrupted output in mesa-demo/fp-tri using r600g on evergreen

[Bug 43332] New: corrupted output in mesa-demo/fp-tri using r600g on evergreen

[bugzilla-daemon]

https://bugs.freedesktop.org/show_bug.cgi?id=43332

             Bug #: 43332
           Summary: corrupted output in mesa-demo/fp-tri using r600g on
                    evergreen
    Classification: Unclassified
           Product: Mesa
           Version: git
          Platform: x86-64 (AMD64)
        OS/Version: Linux (All)
            Status: NEW
          Severity: normal
          Priority: medium
         Component: Drivers/Gallium/r600
        AssignedTo: dri-devel@lists.freedesktop.org
        ReportedBy: stefano.teso@gmail.com


Hi,

using mesa from git master (commit 76ba431b97087e2d5ca0351e0d613f0812fd1425),
the mesa demo fp-tri, when running the scs.txt shader, displays the correct
output overlayed by random blue-ish blocks (perhaps alpha channel corruption?).

The bug doesn't affect llvmpipe. Only scs.txt seems to trigger the issue.

This is on evergreen hw:

01:00.0 VGA compatible controller: ATI Technologies Inc Robson CE [AMD Radeon
HD 6300 Series]

on an i7 machine with i386 debian unstable.

The bug is also present in the libGL 7.11.2 shipped by debian, so I don't think
it's a regression or a bug in my config.

Please let me know if you need more info.

Thanks,

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[Bug 43332] corrupted output in mesa-demo/fp-tri using r600g on evergreen

[bugzilla-daemon]

https://bugs.freedesktop.org/show_bug.cgi?id=43332

--- Comment #1 from Stefano Teso <stefano.teso@gmail.com> 2011-11-29 03:10:30 UTC ---
Created attachment 53948
  --> https://bugs.freedesktop.org/attachment.cgi?id=53948
screenshot showing the artifact

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[Bug 43332] corrupted output in mesa-demo/fp-tri using r600g on evergreen

[bugzilla-daemon]

https://bugs.freedesktop.org/show_bug.cgi?id=43332

--- Comment #2 from Stefano Teso <stefano.teso@gmail.com> 2011-12-15 09:37:46 PST ---
> The bug is also present in the libGL 7.11.2 shipped by debian, so I don't think
> it's a regression or a bug in my config.

It looks like that inst->Dst[0].Register.WriteMask == 3 in tgsi_scs (), so the
ZW components of the dest register are never written. Perhaps this could
explain the artifact. Not that I'm a GL expert or anything ;-)

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[Bug 43332] corrupted output in mesa-demo/fp-tri using r600g on evergreen

[bugzilla-daemon]

https://bugs.freedesktop.org/show_bug.cgi?id=43332

--- Comment #3 from Stefano Teso <stefano.teso@gmail.com> 2011-12-15 09:53:39 PST ---
(In reply to comment #2)
> > The bug is also present in the libGL 7.11.2 shipped by debian, so I don't think
> > it's a regression or a bug in my config.
> 
> It looks like that inst->Dst[0].Register.WriteMask == 3 in tgsi_scs (), so the
> ZW components of the dest register are never written. Perhaps this could
> explain the artifact. Not that I'm a GL expert or anything ;-)

Forcing the mask to 15 fixes the problem. Of course this is no solution. Likely
the fragment color is not cleared properly before calling SCS?

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[Bug 43332] corrupted output in mesa-demo/fp-tri using r600g

[bugzilla-daemon]

https://bugs.freedesktop.org/show_bug.cgi?id=43332

Michel Dänzer <michel@daenzer.net> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|corrupted output in         |corrupted output in
                   |mesa-demo/fp-tri using      |mesa-demo/fp-tri using
                   |r600g on evergreen          |r600g

--- Comment #4 from Michel Dänzer <michel@daenzer.net> 2011-12-16 02:15:25 PST ---
Yeah, looks like the problem is basically that the pixel shader never writes
any explicit values to the ZW components of the output register. However, I'm
not sure offhand if it's the responsibility of the Gallium driver / state
tracker / shader compiler / app to ensure this. Before I go wading through the
various specifications, I hope someone does know offhand. :)

Also seeing it on an RS880, dropping evergreen from the title.

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[Bug 43332] corrupted output in mesa-demo/fp-tri using r600g

[bugzilla-daemon]

https://bugs.freedesktop.org/show_bug.cgi?id=43332

--- Comment #5 from Vadim <ptpzz@yandex.ru> 2011-12-16 08:46:02 PST ---
The shader is responsible for writing all components of the color. SCS
instruction writes XY only (ARB_fragment_program spec), so it's not the
driver's fault.

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[Bug 43332] corrupted output in mesa-demo/fp-tri using r600g

[bugzilla-daemon]

https://bugs.freedesktop.org/show_bug.cgi?id=43332

Michel Dänzer <michel@daenzer.net> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|dri-devel@lists.freedesktop |mesa-dev@lists.freedesktop.
                   |.org                        |org
          Component|Drivers/Gallium/r600        |Demos

--- Comment #6 from Michel Dänzer <michel@daenzer.net> 2011-12-29 09:13:35 PST ---
Reassigning to demos per comment #5.

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