[Bug 33867] [bisected] Graphics corruption related to pageflip ioctl support in 2.6.38-rc*

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=33867

--- Comment #6 from Dave Witbrodt <dawitbro at sbcglobal.net> 2011-02-05 11:04:22 PST ---
Part 4:  Request for guidance


I would like to continue helping track this bug down.  It is only causing a
minor glitch for me, but it is clearly a regression and may have more of an
impact on software I have not tested (or on other people's systems).

The glitch I am observing reminds me of what was reported in bug #33918,
specifically the difference between the 2 versions of 'test07.jpg' images. 
There is also the DRM error msg (see Comment 2) which appears when
'prboom-plus' exhibits the black fade/melt problem:

    [drm:radeon_cs_ioctl] *ERROR* Failed to parse relocation -35!

My bisecting pointed directly at

    6f34be50  drm/radeon/kms: add pageflip ioctl support (v3)

which first causes hangs -- probably irrelevant, since the hangs cease once the
patch series is completed -- and then leaves me with the all-black fades/melts
once non-hanging kernels appear again after the TTM series.

The driver issue in #33918 made me wonder:  if the pageflip support is actually
involved here, what if I go back to an old driver before pageflip support was
added, and use the new kernel with the pageflip DRM bits?

I have tested that, and here is my current situation:

    $ uname -r
    2.6.37+drm2.6.38-rc3.110201.desktop.kms

    $ apt-cache policy xserver-xorg-video-radeon | grep "Installed"
      Installed: 1:6.13.99+git101203.f9bbb26

I am running my 2.6.37 + cherry-picks kernel with the radeon driver from the
last commit before pageflip support was added.  I get no glitches in
'prboom-plus', and all my test software works just fine.

I hope these results are meaningful.  I don't know how to proceed further, so
if I could get some guidance I might be able to help pin the problem down even
further.

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