Merge branch 'drm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6

* 'drm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6:
  drm/i915: fix memory corruption with GM965 and >4GB RAM

1 files changed, 11 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index 17bd766f2081..e33d9be7df3b 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -1895,6 +1895,17 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags)
         if (IS_GEN2(dev))
                 dma_set_coherent_mask(&dev->pdev->dev, DMA_BIT_MASK(30));
 
+        /* 965GM sometimes incorrectly writes to hardware status page (HWS)
+         * using 32bit addressing, overwriting memory if HWS is located
+         * above 4GB.
+         *
+         * The documentation also mentions an issue with undefined
+         * behaviour if any general state is accessed within a page above 4GB,
+         * which also needs to be handled carefully.
+         */
+        if (IS_BROADWATER(dev) || IS_CRESTLINE(dev))
+                dma_set_coherent_mask(&dev->pdev->dev, DMA_BIT_MASK(32));
+
         mmio_bar = IS_GEN2(dev) ? 1 : 0;
         dev_priv->regs = pci_iomap(dev->pdev, mmio_bar, 0);
         if (!dev_priv->regs) {