diff options
| author | Marek Szyprowski <m.szyprowski@samsung.com> | 2020-05-11 12:27:54 +0200 |
|---|---|---|
| committer | Marek Szyprowski <m.szyprowski@samsung.com> | 2020-09-10 08:17:48 +0200 |
| commit | 6c6fa39ca958d5313ff90d3e6c3064e0043c1da3 (patch) | |
| tree | bf3ae1419f202c5c78db606fbed19b5471075603 /drivers/gpu/drm/drm_gem_shmem_helper.c | |
| parent | 0552daac2d18fc92c71c94492476b8eb521227e9 (diff) | |
drm: core: 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>
Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Diffstat (limited to 'drivers/gpu/drm/drm_gem_shmem_helper.c')
| -rw-r--r-- | drivers/gpu/drm/drm_gem_shmem_helper.c | 14 |
1 files changed, 9 insertions, 5 deletions
diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c index 4b7cfbac4daa..47d8211221f2 100644 --- a/drivers/gpu/drm/drm_gem_shmem_helper.c +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c @@ -126,8 +126,8 @@ void drm_gem_shmem_free_object(struct drm_gem_object *obj) drm_prime_gem_destroy(obj, shmem->sgt); } else { if (shmem->sgt) { - dma_unmap_sg(obj->dev->dev, shmem->sgt->sgl, - shmem->sgt->nents, DMA_BIDIRECTIONAL); + dma_unmap_sgtable(obj->dev->dev, shmem->sgt, + DMA_BIDIRECTIONAL, 0); sg_free_table(shmem->sgt); kfree(shmem->sgt); } @@ -424,8 +424,7 @@ void drm_gem_shmem_purge_locked(struct drm_gem_object *obj) WARN_ON(!drm_gem_shmem_is_purgeable(shmem)); - dma_unmap_sg(obj->dev->dev, shmem->sgt->sgl, - shmem->sgt->nents, DMA_BIDIRECTIONAL); + dma_unmap_sgtable(obj->dev->dev, shmem->sgt, DMA_BIDIRECTIONAL, 0); sg_free_table(shmem->sgt); kfree(shmem->sgt); shmem->sgt = NULL; @@ -697,12 +696,17 @@ struct sg_table *drm_gem_shmem_get_pages_sgt(struct drm_gem_object *obj) goto err_put_pages; } /* Map the pages for use by the h/w. */ - dma_map_sg(obj->dev->dev, sgt->sgl, sgt->nents, DMA_BIDIRECTIONAL); + ret = dma_map_sgtable(obj->dev->dev, sgt, DMA_BIDIRECTIONAL, 0); + if (ret) + goto err_free_sgt; shmem->sgt = sgt; return sgt; +err_free_sgt: + sg_free_table(sgt); + kfree(sgt); err_put_pages: drm_gem_shmem_put_pages(shmem); return ERR_PTR(ret); |