1 files changed, 20 insertions, 6 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 1855e72859a8..9cdeeef5d6d7 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -304,12 +304,25 @@ i915_gem_shmem_pread(struct drm_device *dev,
         int shmem_page_offset, page_length, ret = 0;
         int obj_do_bit17_swizzling, page_do_bit17_swizzling;
         int hit_slowpath = 0;
+        int needs_clflush = 0;
 
         user_data = (char __user *) (uintptr_t) args->data_ptr;
         remain = args->size;
 
         obj_do_bit17_swizzling = i915_gem_object_needs_bit17_swizzle(obj);
 
+        if (!(obj->base.read_domains & I915_GEM_DOMAIN_CPU)) {
+                /* If we're not in the cpu read domain, set ourself into the gtt
+                 * read domain and manually flush cachelines (if required). This
+                 * optimizes for the case when the gpu will dirty the data
+                 * anyway again before the next pread happens. */
+                if (obj->cache_level == I915_CACHE_NONE)
+                        needs_clflush = 1;
+                ret = i915_gem_object_set_to_gtt_domain(obj, false);
+                if (ret)
+                        return ret;
+        }
+
         offset = args->offset;
 
         while (remain > 0) {
@@ -337,6 +350,9 @@ i915_gem_shmem_pread(struct drm_device *dev,
 
                 if (!page_do_bit17_swizzling) {
                         vaddr = kmap_atomic(page);
+                        if (needs_clflush)
+                                drm_clflush_virt_range(vaddr + shmem_page_offset,
+                                                       page_length);
                         ret = __copy_to_user_inatomic(user_data,
                                                       vaddr + shmem_page_offset,
                                                       page_length);
@@ -350,6 +366,10 @@ i915_gem_shmem_pread(struct drm_device *dev,
                 mutex_unlock(&dev->struct_mutex);
 
                 vaddr = kmap(page);
+                if (needs_clflush)
+                        drm_clflush_virt_range(vaddr + shmem_page_offset,
+                                               page_length);
+
                 if (page_do_bit17_swizzling)
                         ret = __copy_to_user_swizzled(user_data,
                                                       vaddr, shmem_page_offset,
@@ -430,12 +450,6 @@ i915_gem_pread_ioctl(struct drm_device *dev, void *data,
 
         trace_i915_gem_object_pread(obj, args->offset, args->size);
 
-        ret = i915_gem_object_set_cpu_read_domain_range(obj,
-                                                        args->offset,
-                                                        args->size);
-        if (ret)
-                goto out;
-
         ret = i915_gem_shmem_pread(dev, obj, args, file);
 
 out: