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drm: gem_cma_helper.c: Allow importing of contiguous scatterlists with nents > 1 

drm_gem_cma_prime_import_sg_table() will fail if the number of entries
in the sg_table > 1. However, you can have a device that uses an IOMMU
engine and can map a discontiguous buffer with multiple entries that
have consecutive sg_dma_addresses, effectively making it contiguous.
Allow for that scenario by testing the entries in the sg_table for
contiguous coverage.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Liviu Dudau <liviu.dudau@arm.com>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20171110133310.1225-1-Liviu.Dudau@arm.com
This commit is contained in:
Liviu Dudau 2017-11-10 13:33:10 +00:00 committed by Noralf Trønnes
parent 1f2d9bdc90
commit 998fb1a0f4
2 changed files with 23 additions and 3 deletions
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20
drivers/gpu/drm/drm_gem_cma_helper.c
View File

@ -475,9 +475,27 @@ drm_gem_cma_prime_import_sg_table(struct drm_device *dev,
{
struct drm_gem_cma_object *cma_obj;
if (sgt->nents != 1)
if (sgt->nents != 1) {
/* check if the entries in the sg_table are contiguous */
dma_addr_t next_addr = sg_dma_address(sgt->sgl);
struct scatterlist *s;
unsigned int i;
for_each_sg(sgt->sgl, s, sgt->nents, i) {
/*
* sg_dma_address(s) is only valid for entries
* that have sg_dma_len(s) != 0
*/
if (!sg_dma_len(s))
continue;
if (sg_dma_address(s) != next_addr)
return ERR_PTR(-EINVAL);
next_addr = sg_dma_address(s) + sg_dma_len(s);
}
}
/* Create a CMA GEM buffer. */
cma_obj = __drm_gem_cma_create(dev, attach->dmabuf->size);
if (IS_ERR(cma_obj))

4
include/drm/drm_gem_cma_helper.h
View File

@ -8,7 +8,9 @@
* struct drm_gem_cma_object - GEM object backed by CMA memory allocations
* @base: base GEM object
* @paddr: physical address of the backing memory
* @sgt: scatter/gather table for imported PRIME buffers
* @sgt: scatter/gather table for imported PRIME buffers. The table can have
* more than one entry but they are guaranteed to have contiguous
* DMA addresses.
* @vaddr: kernel virtual address of the backing memory
*/
struct drm_gem_cma_object {