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authorMarek Szyprowski <m.szyprowski@samsung.com>2020-05-04 13:12:07 +0200
committerMarek Szyprowski <m.szyprowski@samsung.com>2020-09-10 08:18:35 +0200
commitb827e3ac4185a6091b90263b6516b54a766c109e (patch)
tree623092327a6f3cfba201c0fb9f175bd5fc69de09 /drivers/gpu
parent84404614167b829f7b58189cd24b6c0c74897171 (diff)
drm: i915: 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. This driver creatively uses sg_table->orig_nents to store the size of the allocated scatterlist and ignores the number of the entries returned by dma_map_sg function. The sg_table->orig_nents is (mis)used to properly free the (over)allocated scatterlist. This patch only introduces the common DMA-mapping wrappers operating directly on the struct sg_table objects to the dmabuf related functions, so the other drivers, which might share buffers with i915 could rely on the properly set nents and orig_nents values. Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> Reviewed-by: Robin Murphy <robin.murphy@arm.com> Reviewed-by: Michael J. Ruhl <michael.j.ruhl@intel.com>
Diffstat (limited to 'drivers/gpu')
-rw-r--r--drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c11
-rw-r--r--drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c7
2 files changed, 6 insertions, 12 deletions
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
index 2679380159fc..8a988592715b 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
@@ -48,12 +48,9 @@ static struct sg_table *i915_gem_map_dma_buf(struct dma_buf_attachment *attachme
src = sg_next(src);
}
- if (!dma_map_sg_attrs(attachment->dev,
- st->sgl, st->nents, dir,
- DMA_ATTR_SKIP_CPU_SYNC)) {
- ret = -ENOMEM;
+ ret = dma_map_sgtable(attachment->dev, st, dir, DMA_ATTR_SKIP_CPU_SYNC);
+ if (ret)
goto err_free_sg;
- }
return st;
@@ -73,9 +70,7 @@ static void i915_gem_unmap_dma_buf(struct dma_buf_attachment *attachment,
{
struct drm_i915_gem_object *obj = dma_buf_to_obj(attachment->dmabuf);
- dma_unmap_sg_attrs(attachment->dev,
- sg->sgl, sg->nents, dir,
- DMA_ATTR_SKIP_CPU_SYNC);
+ dma_unmap_sgtable(attachment->dev, sg, dir, DMA_ATTR_SKIP_CPU_SYNC);
sg_free_table(sg);
kfree(sg);
diff --git a/drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c b/drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c
index debaf7b18ab5..be30b27e2926 100644
--- a/drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c
+++ b/drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c
@@ -28,10 +28,9 @@ static struct sg_table *mock_map_dma_buf(struct dma_buf_attachment *attachment,
sg = sg_next(sg);
}
- if (!dma_map_sg(attachment->dev, st->sgl, st->nents, dir)) {
- err = -ENOMEM;
+ err = dma_map_sgtable(attachment->dev, st, dir, 0);
+ if (err)
goto err_st;
- }
return st;
@@ -46,7 +45,7 @@ static void mock_unmap_dma_buf(struct dma_buf_attachment *attachment,
struct sg_table *st,
enum dma_data_direction dir)
{
- dma_unmap_sg(attachment->dev, st->sgl, st->nents, dir);
+ dma_unmap_sgtable(attachment->dev, st, dir, 0);
sg_free_table(st);
kfree(st);
}