System Environment:
--------------------------
--Platform: FC6
--Xf86_video_intel:96246c27cb836bae8ee02c46c68a1f2102efd14b
--Mesa:aac2d99dc316c069faa46dd43ff034155754c6b3
--DRM:b9417f41418321d5081547a3a3386dcccae7541f
--Kernel:2.6.23

Bug detailed description:
--------------------------
this issue doesn't happen when INTEL_NO_TTM is set
this issue doesn't happen on 965


Reproduce steps:
----------------
start X
run glean case blendFunc by:
./glean -r log -t +blendFunc

Current result:
----------------
get many FAILURE:
blendFunc:  FAIL rgba8, db, z24, s8, win+pmap, id 33
        source factor = GL_DST_COLOR, dest factor = GL_ONE_MINUS_DST_ALPHA
        Readback had 0 bits in error; blending had 7.83184 bits in error.
blendFunc:  FAIL rgba8, db, z24, s8, win+pmap, id 33
        source factor = GL_ONE_MINUS_DST_COLOR, dest factor = GL_ONE_MINUS_SRC_A                                             LPHA
        Readback had 0 bits in error; blending had 7.94538 bits in error.
blendFunc:  FAIL rgba8, db, z24, s8, win+pmap, id 33
        source factor = GL_ONE_MINUS_SRC_ALPHA, dest factor = GL_ZERO
        Readback had 7.32757 bits in error; blending had 0 bits in error.
blendFunc:  FAIL rgba8, db, z24, s8, win+pmap, id 33
        source factor = GL_ONE_MINUS_SRC_ALPHA, dest factor = GL_ONE_MINUS_SRC_C                                             OLOR
        Readback had 7.8322 bits in error; blending had 7.4847 bits in error.
blendFunc:  FAIL rgba8, db, z24, s8, win+pmap, id 33
        source factor = GL_SRC_ALPHA_SATURATE, dest factor = GL_ZERO
        Readback had 0 bits in error; blending had 7.78216 bits in error.
blendFunc:  FAIL rgba8, db, z24, s8, win+pmap, id 34
        source factor = GL_ONE, dest factor = GL_SRC_COLOR
        Readback had 7.94816 bits in error; blending had 6.38069 bits in error.
blendFunc:  FAIL rgba8, db, z24, s8, win+pmap, id 34
        source factor = GL_DST_COLOR, dest factor = GL_ONE
        Readback had 0 bits in error; blending had 5.57889 bits in error.
blendFunc:  FAIL rgba8, db, z24, s8, win+pmap, id 34
        source factor = GL_ONE_MINUS_DST_COLOR, dest factor = GL_ONE_MINUS_SRC_C                                             OLOR
        Readback had 0 bits in error; blending had 6.45012 bits in error.
blendFunc:  FAIL rgba8, db, z24, s8, win+pmap, id 34
        source factor = GL_SRC_ALPHA, dest factor = GL_SRC_COLOR
        Readback had 0 bits in error; blending had 6.11057 bits in error.
blendFunc:  FAIL rgba8, db, z24, s8, win+pmap, id 34
        source factor = GL_ONE_MINUS_SRC_ALPHA, dest factor = GL_ZERO
        Readback had 7.91854 bits in error; blending had 0 bits in error.
blendFunc:  FAIL rgba8, db, z24, s8, win+pmap, id 34
        source factor = GL_ONE_MINUS_SRC_ALPHA, dest factor = GL_SRC_ALPHA
        Readback had 7.37197 bits in error; blending had 7.1102 bits in error.
blendFunc:  FAIL rgba8, win+pmap, id 100
        source factor = GL_ZERO, dest factor = GL_ZERO
        Readback had 7.73357 bits in error; blending had 0 bits in error.
blendFunc:  FAIL rgba8, win+pmap, id 100
        source factor = GL_ZERO, dest factor = GL_ONE_MINUS_SRC_COLOR
        Readback had 0 bits in error; blending had 7.88418 bits in error.
blendFunc:  FAIL rgba8, win+pmap, id 100
        source factor = GL_DST_COLOR, dest factor = GL_SRC_ALPHA
        Readback had 0 bits in error; blending had 4.85111 bits in error.
blendFunc:  FAIL rgba8, win+pmap, id 100
        source factor = GL_DST_COLOR, dest factor = GL_ONE_MINUS_DST_ALPHA
        Readback had 7.91254 bits in error; blending had 6.85438 bits in error.


Expected result:
----------------
Glean case blendFunc should pass