On Thu, Jan 09, 2014 at 11:01:56AM +0530, akash.goel@xxxxxxxxx wrote:
> From: Akash Goel <akash.goel@xxxxxxxxx>
>
> 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 <akash.goel@xxxxxxxxx>
> ---
> 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];
Pre-gen6 has the blitter on the RCS ring.
> + uint32_t obj_height = (obj->base.size / obj->stride);
obj->stride is 0 for untiled buffers, so for more robustness I'd just use
4096 (page size) as stride. For even more robustness I think we should
have checks here to make sure that we don't overflow blitter hw limits
here.
> + 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)
These #defines imo don't help readability, everywhere else
(kernel/userspace) we construct the cmd dwords in-line in the
OUT_BATCH/intel_ring_emit calls. Also please use the existing XY_ blt cmd
#defines in i915_reg.h.
- Daniel
> +
> + 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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--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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