drm/i915: enable 36bit physical address for hardware status page

This enables possible 36bit address mask on 965G that use physical
address for hw status page.

Signed-off-by: Zhenyu Wang <zhenyuw@linux.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 bbe4781..e660ac0 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -134,6 +134,10 @@
 
 	memset(dev_priv->hw_status_page, 0, PAGE_SIZE);
 
+	if (IS_I965G(dev))
+		dev_priv->dma_status_page |= (dev_priv->dma_status_page >> 28) &
+					     0xf0;
+
 	I915_WRITE(HWS_PGA, dev_priv->dma_status_page);
 	DRM_DEBUG_DRIVER("Enabled hardware status page\n");
 	return 0;