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Commit 73f522ba authored by Ville Syrjälä's avatar Ville Syrjälä
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drm/i915: Use i915_gem_object_get_dma_address() to populate rotated vmas 



Replace the kvmalloc_array() with i915_gem_object_get_dma_address() when
populating rotated vmas. One random access mechanism ought to be enough
for everyone?

To calculate the size of the radix tree I think we can do
something like this (assuming 64bit pointers):
 num_pages = obj_size / 4096
 tree_height = ceil(log64(num_pages))
 num_nodes = sum(64^n, n, 0, tree_height-1)
 tree_size = num_nodes * 576

If we compare that with the object size we should get a relative
overhead of around .2% to 1% for reasonable sized objects,
which framebuffers tend to be.

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Suggested-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: default avatarVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181016150413.11577-1-ville.syrjala@linux.intel.com


Reviewed-by: default avatarTvrtko Ursulin <tvrtko.ursulin@intel.com>
parent 198a2a2f

drivers/gpu/drm/i915/i915_gem_gtt.c

+6 −25
Original line number Original line Diff line number Diff line
@@ -3637,7 +3637,7 @@ void i915_gem_restore_gtt_mappings(struct drm_i915_private *dev_priv) 
}

}





static struct scatterlist *

static struct scatterlist *

rotate_pages(const dma_addr_t *in, unsigned int offset,

rotate_pages(struct drm_i915_gem_object *obj, unsigned int offset,

	     unsigned int width, unsigned int height,

	     unsigned int width, unsigned int height,

	     unsigned int stride,

	     unsigned int stride,

	     struct sg_table *st, struct scatterlist *sg)

	     struct sg_table *st, struct scatterlist *sg)
@@ -3646,7 +3646,7 @@ rotate_pages(const dma_addr_t *in, unsigned int offset, 
	unsigned int src_idx;

	unsigned int src_idx;





	for (column = 0; column < width; column++) {

	for (column = 0; column < width; column++) {

		src_idx = stride * (height - 1) + column;

		src_idx = stride * (height - 1) + column + offset;

		for (row = 0; row < height; row++) {

		for (row = 0; row < height; row++) {

			st->nents++;

			st->nents++;

			/* We don't need the pages, but need to initialize

			/* We don't need the pages, but need to initialize
@@ -3654,7 +3654,8 @@ rotate_pages(const dma_addr_t *in, unsigned int offset, 
			 * The only thing we need are DMA addresses.

			 * The only thing we need are DMA addresses.

			 */

			 */

			sg_set_page(sg, NULL, I915_GTT_PAGE_SIZE, 0);

			sg_set_page(sg, NULL, I915_GTT_PAGE_SIZE, 0);

			sg_dma_address(sg) = in[offset + src_idx];

			sg_dma_address(sg) =

				i915_gem_object_get_dma_address(obj, src_idx);

			sg_dma_len(sg) = I915_GTT_PAGE_SIZE;

			sg_dma_len(sg) = I915_GTT_PAGE_SIZE;

			sg = sg_next(sg);

			sg = sg_next(sg);

			src_idx -= stride;

			src_idx -= stride;
@@ -3668,22 +3669,11 @@ static noinline struct sg_table * 
intel_rotate_pages(struct intel_rotation_info *rot_info,

intel_rotate_pages(struct intel_rotation_info *rot_info,

		   struct drm_i915_gem_object *obj)

		   struct drm_i915_gem_object *obj)

{

{

	const unsigned long n_pages = obj->base.size / I915_GTT_PAGE_SIZE;

	unsigned int size = intel_rotation_info_size(rot_info);

	unsigned int size = intel_rotation_info_size(rot_info);

	struct sgt_iter sgt_iter;

	dma_addr_t dma_addr;

	unsigned long i;

	dma_addr_t *page_addr_list;

	struct sg_table *st;

	struct sg_table *st;

	struct scatterlist *sg;

	struct scatterlist *sg;

	int ret = -ENOMEM;

	int ret = -ENOMEM;



	int i;

	/* Allocate a temporary list of source pages for random access. */

	page_addr_list = kvmalloc_array(n_pages,

					sizeof(dma_addr_t),

					GFP_KERNEL);

	if (!page_addr_list)

		return ERR_PTR(ret);





	/* Allocate target SG list. */

	/* Allocate target SG list. */

	st = kmalloc(sizeof(*st), GFP_KERNEL);

	st = kmalloc(sizeof(*st), GFP_KERNEL);
@@ -3694,29 +3684,20 @@ intel_rotate_pages(struct intel_rotation_info *rot_info, 
	if (ret)

	if (ret)

		goto err_sg_alloc;

		goto err_sg_alloc;





	/* Populate source page list from the object. */

	i = 0;

	for_each_sgt_dma(dma_addr, sgt_iter, obj->mm.pages)

		page_addr_list[i++] = dma_addr;



	GEM_BUG_ON(i != n_pages);

	st->nents = 0;

	st->nents = 0;

	sg = st->sgl;

	sg = st->sgl;





	for (i = 0 ; i < ARRAY_SIZE(rot_info->plane); i++) {

	for (i = 0 ; i < ARRAY_SIZE(rot_info->plane); i++) {

		sg = rotate_pages(page_addr_list, rot_info->plane[i].offset,

		sg = rotate_pages(obj, rot_info->plane[i].offset,

				  rot_info->plane[i].width, rot_info->plane[i].height,

				  rot_info->plane[i].width, rot_info->plane[i].height,

				  rot_info->plane[i].stride, st, sg);

				  rot_info->plane[i].stride, st, sg);

	}

	}





	kvfree(page_addr_list);



	return st;

	return st;





err_sg_alloc:

err_sg_alloc:

	kfree(st);

	kfree(st);

err_st_alloc:

err_st_alloc:

	kvfree(page_addr_list);





	DRM_DEBUG_DRIVER("Failed to create rotated mapping for object size %zu! (%ux%u tiles, %u pages)\n",

	DRM_DEBUG_DRIVER("Failed to create rotated mapping for object size %zu! (%ux%u tiles, %u pages)\n",

			 obj->base.size, rot_info->plane[0].width, rot_info->plane[0].height, size);

			 obj->base.size, rot_info->plane[0].width, rot_info->plane[0].height, size);