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

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@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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 1f61fc7b754..2d6039b4571 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -863,7 +863,7 @@ 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;