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drm/i915: Use i915_gem_object_get_dma_address() to populate rotated vmas

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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: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181016150413.11577-1-ville.syrjala@linux.intel.com
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
This commit is contained in:
Ville Syrjälä 2018-10-16 18:04:13 +03:00
parent 198a2a2f1a
commit 73f522bad1
1 changed files with 6 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

31
drivers/gpu/drm/i915/i915_gem_gtt.c
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@ -3637,7 +3637,7 @@ void i915_gem_restore_gtt_mappings(struct drm_i915_private *dev_priv)
}
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 stride,
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;
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++) {
st->nents++;
/* 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.
*/
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 = sg_next(sg);
src_idx -= stride;
@ -3668,22 +3669,11 @@ static noinline struct sg_table *
intel_rotate_pages(struct intel_rotation_info *rot_info,
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);
struct sgt_iter sgt_iter;
dma_addr_t dma_addr;
unsigned long i;
dma_addr_t *page_addr_list;
struct sg_table *st;
struct scatterlist *sg;
int ret = -ENOMEM;
/* 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);
int i;
/* Allocate target SG list. */
st = kmalloc(sizeof(*st), GFP_KERNEL);
@ -3694,29 +3684,20 @@ intel_rotate_pages(struct intel_rotation_info *rot_info,
if (ret)
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;
sg = st->sgl;
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].stride, st, sg);
}
kvfree(page_addr_list);
return st;
err_sg_alloc:
kfree(st);
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",
obj->base.size, rot_info->plane[0].width, rot_info->plane[0].height, size);