[Intel-gfx] [PATCH] drm/i915/ringbuffer: Exclude last 2 cachlines of ring on 845g

[Chris Wilson]

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 at chris-wilson.co.uk>
Cc: stable at kernel.org
---
 drivers/gpu/drm/i915/intel_ringbuffer.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 8a6e331..2e9fa1c 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -1042,7 +1042,7 @@ int intel_init_ring_buffer(struct drm_device *dev,
 	 * 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;
 
 	ring->obj = obj;
-- 
1.7.9.5