drm/i915: implement BSD ring buffer V2

The BSD (bit stream decoder) ring is used for accessing the BSD engine
which decodes video bitstream for H.264 and VC1 on G45+.  It is
asynchronous with the render ring and has access to separate parts of
the GPU from it, though the render cache is coherent between the two.

Signed-off-by: Zou Nan hai <nanhai.zou@intel.com>
Signed-off-by: Xiang Hai hao <haihao.xiang@intel.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index f485880..1dbed70 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -130,6 +130,8 @@
 		drm_irq_uninstall(dev);
 
 	intel_cleanup_ring_buffer(dev, &dev_priv->render_ring);
+	if (HAS_BSD(dev))
+		intel_cleanup_ring_buffer(dev, &dev_priv->bsd_ring);
 
 	/* Clear the HWS virtual address at teardown */
 	if (I915_NEED_GFX_HWS(dev))