From: Greg KH on
2.6.32-stable review patch. If anyone has any objections, please let us know.


From: Dave Airlie <airlied(a)>

commit 944001201ca0196bcdb088129e5866a9f379d08c upstream.

A lot of 945GMs have had stability issues for a long time, this manifested as X hangs, blitter engine hangs, and lots of crashes.

one such report is at:

along with numerous distro bugzillas.

This only took a week of digging and hair ripping to figure out.

Tracked down and tested on a 945GM Lenovo T60,
previously running
x11perf -copypixwin500
x11perf -copywinpix500
repeatedly would cause the GPU to wedge within 4 or 5 tries, with random busy bits set.

After this patch no hangs were observed.

Signed-off-by: Dave Airlie <airlied(a)>
Signed-off-by: Greg Kroah-Hartman <gregkh(a)>

drivers/gpu/drm/i915/i915_gem.c | 10 ++++++++++
1 file changed, 10 insertions(+)

--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4697,6 +4697,16 @@ i915_gem_load(struct drm_device *dev)
list_add(&dev_priv->mm.shrink_list, &shrink_list);

+ /* On GEN3 we really need to make sure the ARB C3 LP bit is set */
+ if (IS_I915G(dev) || IS_I915GM(dev) || IS_I945G(dev) || IS_I945GM(dev) || IS_G33(dev)) {
+ u32 tmp = I915_READ(MI_ARB_STATE);
+ if (!(tmp & MI_ARB_C3_LP_WRITE_ENABLE)) {
+ /* arb state is a masked write, so set bit + bit in mask */
+ I915_WRITE(MI_ARB_STATE, tmp);
+ }
+ }
/* Old X drivers will take 0-2 for front, back, depth buffers */
dev_priv->fence_reg_start = 3;

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo(a)
More majordomo info at
Please read the FAQ at