From: Akash Goel <[email protected]>

On VLV, to clear out the contents of Frame buffers allocated from
stolen area, Blitter engine is being used, to avoid the waste of
CPU cycles in doing a sw based memset.

Signed-off-by: Akash Goel <[email protected]>
---
 drivers/gpu/drm/i915/i915_gem_stolen.c | 87 ++++++++++++++++++++++++++++++++--
 1 file changed, 84 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_stolen.c 
b/drivers/gpu/drm/i915/i915_gem_stolen.c
index 253a39a..10237c8 100644
--- a/drivers/gpu/drm/i915/i915_gem_stolen.c
+++ b/drivers/gpu/drm/i915/i915_gem_stolen.c
@@ -371,7 +371,84 @@ i915_gem_object_create_stolen(struct drm_device *dev, u32 
size)
        return NULL;
 }
 
-static void i915_memset_stolen_obj(struct drm_i915_gem_object *obj)
+static int i915_add_clear_obj_cmd(struct drm_i915_gem_object *obj)
+{
+       struct drm_i915_private *dev_priv = obj->base.dev->dev_private;
+       struct intel_ring_buffer *ring = &dev_priv->ring[BCS];
+       uint32_t obj_height = (obj->base.size / obj->stride);
+       u32 offset = i915_gem_obj_ggtt_offset(obj);
+       int ret;
+
+#define        COLOR_BLIT_OP           ((0x2 << 29) | (0x40 << 22) | (0x3 << 
20) | 0x3)
+#define        COLOR_BLIT_OP_DW1       ((0x3 << 24) | (0xF0 << 16) | 
(obj->stride))
+#define        COLOR_BLIT_OP_DW2       ((obj_height << 16) | (obj->stride))
+#define        COLOR_BLIT_OP_DW3       (offset)
+#define        COLOR_BLIT_OP_DW4       (0x0)
+
+       ret = intel_ring_begin(ring, 6);
+       if (ret)
+               return ret;
+       intel_ring_emit(ring, COLOR_BLIT_OP);
+       intel_ring_emit(ring, COLOR_BLIT_OP_DW1);
+       intel_ring_emit(ring, COLOR_BLIT_OP_DW2);
+       intel_ring_emit(ring, COLOR_BLIT_OP_DW3);
+       intel_ring_emit(ring, COLOR_BLIT_OP_DW4);
+       intel_ring_emit(ring, MI_NOOP);
+       intel_ring_advance(ring);
+
+       return 0;
+}
+
+static int i915_memset_stolen_obj_hw(struct drm_i915_gem_object *obj)
+{
+       struct drm_i915_private *dev_priv = obj->base.dev->dev_private;
+       struct intel_ring_buffer *ring = &dev_priv->ring[BCS];
+       unsigned alignment = 0;
+       bool map_and_fenceable =  true;
+       bool nonblocking = false;
+       u32 seqno;
+       int ret;
+
+       ret = i915_gem_obj_ggtt_pin(obj, alignment, map_and_fenceable,
+               nonblocking);
+       if (ret) {
+               DRM_ERROR("Mapping of User FB to GTT failed\n");
+               return ret;
+       }
+
+       /* Adding commands to the blitter ring to
+        * clear out the contents of the buffer object
+        */
+       ret = i915_add_clear_obj_cmd(obj);
+       if (ret) {
+               DRM_ERROR("couldn't add commands in blitter ring\n");
+               i915_gem_object_ggtt_unpin(obj);
+               return ret;
+       }
+
+       seqno = intel_ring_get_seqno(ring);
+
+       /* Object now in render domain */
+       obj->base.read_domains = I915_GEM_DOMAIN_RENDER;
+       obj->base.write_domain = I915_GEM_DOMAIN_RENDER;
+
+       i915_vma_move_to_active(i915_gem_obj_to_ggtt(obj), ring);
+
+       obj->dirty = 1;
+       obj->last_write_seqno = seqno;
+
+       /* Unconditionally force add_request to emit a full flush. */
+       ring->gpu_caches_dirty = true;
+
+       /* Add a breadcrumb for the completion of the clear request */
+       (void)i915_add_request(ring, NULL);
+
+       i915_gem_object_ggtt_unpin(obj);
+
+       return 0;
+}
+
+static void i915_memset_stolen_obj_sw(struct drm_i915_gem_object *obj)
 {
        int ret;
        char __iomem *base;
@@ -490,9 +567,13 @@ i915_gem_object_move_to_stolen(struct drm_i915_gem_object 
*obj)
        obj->cache_level = HAS_LLC(dev) ? I915_CACHE_LLC : I915_CACHE_NONE;
 
        /* Zero-out the contents of the stolen object, otherwise we observe
-        * corruptions in the display.
+        * corruptions in the display. First try using the blitter engine
+        * to clear the buffer contents
         */
-       i915_memset_stolen_obj(obj);
+       ret = i915_memset_stolen_obj_hw(obj);
+       /* fallback to Sw based memset if Hw memset fails */
+       if (ret)
+               i915_memset_stolen_obj_sw(obj);
        return;
 
 cleanup:
-- 
1.8.5.2

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