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author | Marek Szyprowski <m.szyprowski@samsung.com> | 2020-05-08 10:56:57 +0300 |
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committer | Marek Szyprowski <m.szyprowski@samsung.com> | 2020-09-10 09:18:35 +0300 |
commit | 7690a33f22abab03274d9f5337e22c340664bc45 (patch) | |
tree | 8d0a6302074d74ca6cade0773fdc10b769c4072c /drivers/gpu/drm/msm/msm_iommu.c | |
parent | 90dcf4449008cfae24ffd920c0998c09ada46aad (diff) | |
download | linux-7690a33f22abab03274d9f5337e22c340664bc45.tar.xz |
drm: msm: fix common struct sg_table related issues
The Documentation/DMA-API-HOWTO.txt states that the dma_map_sg() function
returns the number of the created entries in the DMA address space.
However the subsequent calls to the dma_sync_sg_for_{device,cpu}() and
dma_unmap_sg must be called with the original number of the entries
passed to the dma_map_sg().
struct sg_table is a common structure used for describing a non-contiguous
memory buffer, used commonly in the DRM and graphics subsystems. It
consists of a scatterlist with memory pages and DMA addresses (sgl entry),
as well as the number of scatterlist entries: CPU pages (orig_nents entry)
and DMA mapped pages (nents entry).
It turned out that it was a common mistake to misuse nents and orig_nents
entries, calling DMA-mapping functions with a wrong number of entries or
ignoring the number of mapped entries returned by the dma_map_sg()
function.
To avoid such issues, lets use a common dma-mapping wrappers operating
directly on the struct sg_table objects and use scatterlist page
iterators where possible. This, almost always, hides references to the
nents and orig_nents entries, making the code robust, easier to follow
and copy/paste safe.
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Rob Clark <robdclark@gmail.com>
Diffstat (limited to 'drivers/gpu/drm/msm/msm_iommu.c')
-rw-r--r-- | drivers/gpu/drm/msm/msm_iommu.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/gpu/drm/msm/msm_iommu.c b/drivers/gpu/drm/msm/msm_iommu.c index 3a381a9674c9..6c31e65834c6 100644 --- a/drivers/gpu/drm/msm/msm_iommu.c +++ b/drivers/gpu/drm/msm/msm_iommu.c @@ -36,7 +36,7 @@ static int msm_iommu_map(struct msm_mmu *mmu, uint64_t iova, struct msm_iommu *iommu = to_msm_iommu(mmu); size_t ret; - ret = iommu_map_sg(iommu->domain, iova, sgt->sgl, sgt->nents, prot); + ret = iommu_map_sgtable(iommu->domain, iova, sgt, prot); WARN_ON(!ret); return (ret == len) ? 0 : -EINVAL; |