From: Liviu Dudau Date: Fri, 10 Nov 2017 13:33:10 +0000 Subject: drm: gem_cma_helper.c: Allow importing of contiguous scatterlists with nents > 1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Git-commit: 998fb1a0f478b83492220ff79583bf9ad538bdd8 Patch-mainline: v4.16-rc1 References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166 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 Signed-off-by: Liviu Dudau Signed-off-by: Noralf Trønnes Link: https://patchwork.freedesktop.org/patch/msgid/20171110133310.1225-1-Liviu.Dudau@arm.com Acked-by: Petr Tesarik --- drivers/gpu/drm/drm_gem_cma_helper.c | 22 ++++++++++++++++++++-- include/drm/drm_gem_cma_helper.h | 4 +++- 2 files changed, 23 insertions(+), 3 deletions(-) --- a/drivers/gpu/drm/drm_gem_cma_helper.c +++ b/drivers/gpu/drm/drm_gem_cma_helper.c @@ -475,8 +475,26 @@ drm_gem_cma_prime_import_sg_table(struct { struct drm_gem_cma_object *cma_obj; - if (sgt->nents != 1) - return ERR_PTR(-EINVAL); + 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); --- a/include/drm/drm_gem_cma_helper.h +++ b/include/drm/drm_gem_cma_helper.h @@ -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 {