3 files changed, 25 insertions, 11 deletions

diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index ee64b7301f67..1e01e7847155 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -966,10 +966,6 @@ static int i915_load_modeset_init(struct drm_device *dev)
         if (ret)
                 goto kfree_devname;
 
-        dev_priv->mm.gtt_mapping =
-                io_mapping_create_wc(dev->agp->base,
-                                     dev->agp->agp_info.aper_size * 1024*1024);
-
         /* Allow hardware batchbuffers unless told otherwise.
          */
         dev_priv->allow_batchbuffer = 1;
@@ -1081,6 +1077,23 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags)
                 goto free_priv;
         }
 
+        dev_priv->mm.gtt_mapping =
+                io_mapping_create_wc(dev->agp->base,
+                                     dev->agp->agp_info.aper_size * 1024*1024);
+        /* Set up a WC MTRR for non-PAT systems.  This is more common than
+         * one would think, because the kernel disables PAT on first
+         * generation Core chips because WC PAT gets overridden by a UC
+         * MTRR if present.  Even if a UC MTRR isn't present.
+         */
+        dev_priv->mm.gtt_mtrr = mtrr_add(dev->agp->base,
+                                         dev->agp->agp_info.aper_size *
+                                         1024 * 1024,
+                                         MTRR_TYPE_WRCOMB, 1);
+        if (dev_priv->mm.gtt_mtrr < 0) {
+                DRM_INFO("MTRR allocation failed\n.  Graphics "
+                         "performance may suffer.\n");
+        }
+
 #ifdef CONFIG_HIGHMEM64G
         /* don't enable GEM on PAE - needs agp + set_memory_* interface fixes */
         dev_priv->has_gem = 0;
@@ -1145,8 +1158,14 @@ int i915_driver_unload(struct drm_device *dev)
 {
         struct drm_i915_private *dev_priv = dev->dev_private;
 
+        io_mapping_free(dev_priv->mm.gtt_mapping);
+        if (dev_priv->mm.gtt_mtrr >= 0) {
+                mtrr_del(dev_priv->mm.gtt_mtrr, dev->agp->base,
+                         dev->agp->agp_info.aper_size * 1024 * 1024);
+                dev_priv->mm.gtt_mtrr = -1;
+        }
+
         if (drm_core_check_feature(dev, DRIVER_MODESET)) {
-                io_mapping_free(dev_priv->mm.gtt_mapping);
                 drm_irq_uninstall(dev);
         }
 
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index e13518252007..f471d218b89a 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -284,6 +284,7 @@ typedef struct drm_i915_private {
                 struct drm_mm gtt_space;
 
                 struct io_mapping *gtt_mapping;
+                int gtt_mtrr;
 
                 /**
                  * List of objects currently involved in rendering from the
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index a590d61ff692..af8034d52511 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -3229,10 +3229,6 @@ i915_gem_entervt_ioctl(struct drm_device *dev, void *data,
                 dev_priv->mm.wedged = 0;
         }
 
-        dev_priv->mm.gtt_mapping = io_mapping_create_wc(dev->agp->base,
-                                                        dev->agp->agp_info.aper_size
-                                                        * 1024 * 1024);
-
         mutex_lock(&dev->struct_mutex);
         dev_priv->mm.suspended = 0;
 
@@ -3255,7 +3251,6 @@ int
 i915_gem_leavevt_ioctl(struct drm_device *dev, void *data,
                        struct drm_file *file_priv)
 {
-        drm_i915_private_t *dev_priv = dev->dev_private;
         int ret;
 
         if (drm_core_check_feature(dev, DRIVER_MODESET))
@@ -3264,7 +3259,6 @@ i915_gem_leavevt_ioctl(struct drm_device *dev, void *data,
         ret = i915_gem_idle(dev);
         drm_irq_uninstall(dev);
 
-        io_mapping_free(dev_priv->mm.gtt_mapping);
         return ret;
 }