System Environment:
--------------------------
Libdrm:         (master)a5c8f55397377994ceeb76ed0ff148ff89eb3a1b
Mesa:           (master)1613735d08eacc4b3d21694e5010587357525ecc
Xf86_video_intel:              
(master)1c3aaad09d6ef207fba748ad4ef4575a26ab2e5c
Xserver:                (master)a34812b09000db2ff2a1dc6182602839123edd4e
Kernel:       (drm-intel-next)d62a57e2ee7be1f7e86047faee6ca5ba7720182f


Bug detailed description:
-------------------------
This issue happens on G45.

Many piglit cases regressed, like:
general/bgra-vert-attrib-pointer
general/bgra-sec-color-pointer
general/depth-clamp-range
general/depth-range-clear
general/occlusion_query
general/pbo-drawpixels
general/scissor-clear
general/scissor-copypixels
general/scissor-depth-clear
general/scissor-stencil-clear

Many glean cases regressed, like:
basicPerf
makeCurrent
occluQry
orthoPosRandTris
orthoPosRandRects
orthoPosTinyQuads
orthoPosHLines
orthoPosVLines
orthoPosPoints
readPixSanity
texCombine4
texEnv


bisect show following commit brings in this issue:
commit d449627829e1a4a3250a1a723af2f4e3cd5fd194
Author: Kristian Høgsberg <krh@bitplanet.net>
Date:   Wed Feb 17 21:17:55 2010 -0500

    intel: Implement the DRI2 invalidate function properly

    This uses a stamp mechanisms to mark the DRI drawable as invalid.
    Instead of immediately updating the buffers we just bump the drawable
    stamp and call out to DRI2GetBuffers "later".

    "Later" used to be at LOCK_HARDWARE time, and this patch brings back
    callouts at the points where we used to call LOCK_HARDWARE.  A new function,
    intel_prepare_render(), is called where we used to call LOCK_HARDWARE,
    and if the buffers are invalid, we call out to DRI2GetBuffers there.

    This lets us invalidate buffers only when notified instead of on
    every glViewport() call.  If the loader calls the DRI invalidate
    entrypoint, we disable viewport triggered buffer invalidation.

    Additionally, we can clean up the old viewport mechanism a bit,
    since we can just invalidate the buffers and not worry about
    reentrancy and whatnot.