From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Mon, 9 Apr 2012 12:59:46 +0000 (+0100)
Subject: drm/i915/ringbuffer: Exclude last 2 cachlines of ring on 845g
X-Git-Url: http://git.alex.org.uk

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

BugLink: http://bugs.launchpad.net/bugs/987337

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>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
---

diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 30a9af9..8673581 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -1052,7 +1052,7 @@ 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;