i915: Map status page cached for chips with GTT-based HWS location.

This should improve performance by avoiding uncached reads by the CPU (the
point of having a status page), and may improve stability.  This patch only
affects G33, GM45 and G45 chips as those are the only ones using GTT-based
HWS mappings.

Signed-off-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>

3 files changed, 21 insertions, 15 deletions

diff --git a/drivers/gpu/drm/drm_agpsupport.c b/drivers/gpu/drm/drm_agpsupport.c
index 2639be2db9e5..3d33b8252b58 100644
--- a/drivers/gpu/drm/drm_agpsupport.c
+++ b/drivers/gpu/drm/drm_agpsupport.c
@@ -464,7 +464,8 @@ DRM_AGP_MEM *
 drm_agp_bind_pages(struct drm_device *dev,
                    struct page **pages,
                    unsigned long num_pages,
-                   uint32_t gtt_offset)
+                   uint32_t gtt_offset,
+                   u32 type)
 {
         DRM_AGP_MEM *mem;
         int ret, i;
@@ -472,7 +473,7 @@ drm_agp_bind_pages(struct drm_device *dev,
         DRM_DEBUG("\n");
 
         mem = drm_agp_allocate_memory(dev->agp->bridge, num_pages,
-                                      AGP_USER_MEMORY);
+                                      type);
         if (mem == NULL) {
                 DRM_ERROR("Failed to allocate memory for %ld pages\n",
                           num_pages);
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index da7c0072ad4c..eae4ed3956e0 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -373,6 +373,9 @@ struct drm_i915_gem_object {
         /** Current tiling mode for the object. */
         uint32_t tiling_mode;
 
+        /** AGP mapping type (AGP_USER_MEMORY or AGP_USER_CACHED_MEMORY */
+        uint32_t agp_type;
+
         /**
          * Flagging of which individual pages are valid in GEM_DOMAIN_CPU when
          * GEM_DOMAIN_CPU is not in the object's read domain.
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 94b9bdce0c75..99a86249bb1b 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1159,7 +1159,8 @@ i915_gem_object_bind_to_gtt(struct drm_gem_object *obj, unsigned alignment)
         obj_priv->agp_mem = drm_agp_bind_pages(dev,
                                                obj_priv->page_list,
                                                page_count,
-                                               obj_priv->gtt_offset);
+                                               obj_priv->gtt_offset,
+                                               obj_priv->agp_type);
         if (obj_priv->agp_mem == NULL) {
                 i915_gem_object_free_page_list(obj);
                 drm_mm_put_block(obj_priv->gtt_space);
@@ -2142,6 +2143,8 @@ int i915_gem_init_object(struct drm_gem_object *obj)
         obj->write_domain = I915_GEM_DOMAIN_CPU;
         obj->read_domains = I915_GEM_DOMAIN_CPU;
 
+        obj_priv->agp_type = AGP_USER_MEMORY;
+
         obj->driver_private = obj_priv;
         obj_priv->obj = obj;
         INIT_LIST_HEAD(&obj_priv->list);
@@ -2311,6 +2314,7 @@ i915_gem_init_hws(struct drm_device *dev)
                 return -ENOMEM;
         }
         obj_priv = obj->driver_private;
+        obj_priv->agp_type = AGP_USER_CACHED_MEMORY;
 
         ret = i915_gem_object_pin(obj, 4096);
         if (ret != 0) {
@@ -2319,25 +2323,18 @@ i915_gem_init_hws(struct drm_device *dev)
         }
 
         dev_priv->status_gfx_addr = obj_priv->gtt_offset;
-        dev_priv->hws_map.offset = dev->agp->base + obj_priv->gtt_offset;
-        dev_priv->hws_map.size = 4096;
-        dev_priv->hws_map.type = 0;
-        dev_priv->hws_map.flags = 0;
-        dev_priv->hws_map.mtrr = 0;
 
-        /* Ioremapping here is the wrong thing to do.  We want cached access.
-         */
-        drm_core_ioremap_wc(&dev_priv->hws_map, dev);
-        if (dev_priv->hws_map.handle == NULL) {
+        dev_priv->hw_status_page = kmap(obj_priv->page_list[0]);
+        if (dev_priv->hw_status_page == NULL) {
                 DRM_ERROR("Failed to map status page.\n");
                 memset(&dev_priv->hws_map, 0, sizeof(dev_priv->hws_map));
                 drm_gem_object_unreference(obj);
                 return -EINVAL;
         }
         dev_priv->hws_obj = obj;
-        dev_priv->hw_status_page = dev_priv->hws_map.handle;
         memset(dev_priv->hw_status_page, 0, PAGE_SIZE);
         I915_WRITE(HWS_PGA, dev_priv->status_gfx_addr);
+        I915_READ(HWS_PGA); /* posting read */
         DRM_DEBUG("hws offset: 0x%08x\n", dev_priv->status_gfx_addr);
 
         return 0;
@@ -2456,10 +2453,15 @@ i915_gem_cleanup_ringbuffer(struct drm_device *dev)
         memset(&dev_priv->ring, 0, sizeof(dev_priv->ring));
 
         if (dev_priv->hws_obj != NULL) {
-                i915_gem_object_unpin(dev_priv->hws_obj);
-                drm_gem_object_unreference(dev_priv->hws_obj);
+                struct drm_gem_object *obj = dev_priv->hws_obj;
+                struct drm_i915_gem_object *obj_priv = obj->driver_private;
+
+                kunmap(obj_priv->page_list[0]);
+                i915_gem_object_unpin(obj);
+                drm_gem_object_unreference(obj);
                 dev_priv->hws_obj = NULL;
                 memset(&dev_priv->hws_map, 0, sizeof(dev_priv->hws_map));
+                dev_priv->hw_status_page = NULL;
 
                 /* Write high address into HWS_PGA when disabling. */
                 I915_WRITE(HWS_PGA, 0x1ffff000);