drm/i915/ringbuffer: Exclude last 2 cachlines of ring on 845g

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@chris-wilson.co.uk>
Cc: stable@kernel.org
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 1 insertions, 1 deletions

diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index e25581a9f60f..f75806e5bff5 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -1038,7 +1038,7 @@ 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;
 
         return 0;