Just ran a bisection, and it pinpoints 6bda10d152735c22baf1dcd92937420b4b0a359a

commit 6bda10d152735c22baf1dcd92937420b4b0a359a
Author: Chris Wilson <email address hidden>
Date:   Sun Dec 5 21:04:18 2010 +0000

    drm/i915: Completely disable fence pipelining.
    
    I'm still seeing tiling corruption of PutImage and CopyArea (I think)
    under mutter on pnv, so obviously the pipelining logic is deeply flawed.
    
    Signed-off-by: Chris Wilson <email address hidden>

Bisection log:
# bad: [944f96a41e0b2a578569ad96c1422afb027907db] UBUNTU: Ubuntu-2.6.38-1.28
# good: [708cdc66d1ca5f0cd7ff8ca44aeadbd7d0706b55] UBUNTU: Ubuntu-2.6.37-12.26
git bisect start 'Ubuntu-2.6.38-1.28' 'Ubuntu-2.6.37-12.26'
# good: [3c0eee3fe6a3a1c745379547c7e7c904aa64f6d5] Linux 2.6.37
git bisect good 3c0eee3fe6a3a1c745379547c7e7c904aa64f6d5
# good: [949f6711b83d2809d1ccb9d830155a65fdacdff9] Merge branch 'staging-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging-2.6
git bisect good 949f6711b83d2809d1ccb9d830155a65fdacdff9
# bad: [fe3c560b8a22cb28e54fe8950abef38e88d75831] Merge branch 'for-linus/i2c-2638' of git://git.fluff.org/bjdooks/linux
git bisect bad fe3c560b8a22cb28e54fe8950abef38e88d75831
# bad: [1b3862798cf4390b9110e54e405646e156f47c83] Merge branch 'tools' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-idle-2.6
git bisect bad 1b3862798cf4390b9110e54e405646e156f47c83
# bad: [42776163e13a56ea3096edff7a5df95408e80eb4] Merge branch 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
git bisect bad 42776163e13a56ea3096edff7a5df95408e80eb4
# bad: [d8c58fabd75021cdd99abcd96513cb088d41092b] Merge remote branch 'airlied/drm-core-next' into drm-intel-next
git bisect bad d8c58fabd75021cdd99abcd96513cb088d41092b
# good: [71f4566084eb592fe545f05f7dff41fa9aa42e0b] agp/intel: Fix missed cached memory flags setting in i965_write_entry()
git bisect good 71f4566084eb592fe545f05f7dff41fa9aa42e0b
# good: [b08ebe7e776e5be0271ed1e1bbb384e1f29dd117] drm/radeon/kms: properly print ontario chip id
git bisect good b08ebe7e776e5be0271ed1e1bbb384e1f29dd117
# good: [0b0b053a3949f5c467c3b3ba135d4c161f9fbd00] drm/i915/panel: Restore saved value of BLC_PWM_CTL
git bisect good 0b0b053a3949f5c467c3b3ba135d4c161f9fbd00
# good: [257e48f1474a1f5bfa6fcafb12f77a8479063293] drm/i915/lvds: Disable panel-fitter on gen4 for 1:1 scale factors
git bisect good 257e48f1474a1f5bfa6fcafb12f77a8479063293
# bad: [6bda10d152735c22baf1dcd92937420b4b0a359a] drm/i915: Completely disable fence pipelining.
git bisect bad 6bda10d152735c22baf1dcd92937420b4b0a359a
# good: [340479aac697bc73e225c122a9753d4964eeda3f] drm/i915: Be paranoid and bail on resetting if we can't take the lock.
git bisect good 340479aac697bc73e225c122a9753d4964eeda3f
# good: [bbf0c6b3620b3872929ef7d3c392ce436889110f] drm/i915: announce to userspace that the bsd ring is coherent
git bisect good bbf0c6b3620b3872929ef7d3c392ce436889110f
# good: [160b1543cdae83e9f8914ac7afc3d2bd686140af] drm/i915/dp: Trivial code tidy
git bisect good 160b1543cdae83e9f8914ac7afc3d2bd686140af
# good: [e3c4e5dd5ad1993a3687862c982272f8f00cae30] drm/i915: caps.has_rc6 is no longer used, remove it.
git bisect good e3c4e5dd5ad1993a3687862c982272f8f00cae30
# good: [0cdab21f9a1fca50dd27e488839f5a6578e333b2] drm/i915: Uncouple render/power ctx before suspending
git bisect good 0cdab21f9a1fca50dd27e488839f5a6578e333b2