[ 04/75] drm/i915/ringbuffer: Exclude last 2 cachlines of ring on 845g

From: Greg KH
Date: Thu Apr 19 2012 - 17:05:06 EST


3.3-stable review patch. If anyone has any objections, please let me know.

------------------

From: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>

commit 27c1cbd06a7620b354cbb363834f3bb8df4f410d upstream.

The 845g shares the errata with i830 whereby executing a command
within 2 cachelines of the end of the ringbuffer may cause a GPU hang.

Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
drivers/gpu/drm/i915/intel_ringbuffer.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -1057,7 +1057,7 @@ int intel_init_ring_buffer(struct drm_de
* of the buffer.
*/
ring->effective_size = ring->size;
- if (IS_I830(ring->dev))
+ if (IS_I830(ring->dev) || IS_845G(ring->dev))
ring->effective_size -= 128;

return 0;


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