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author | Marek Szyprowski <m.szyprowski@samsung.com> | 2020-06-19 13:36:17 +0300 |
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committer | Christian König <christian.koenig@amd.com> | 2020-07-13 11:48:07 +0300 |
commit | 7b814900b8ccb4e61ebe704d42a12dc2d06b4a3a (patch) | |
tree | 18037f6f78253836c3187f779d3b51eae22ff207 | |
parent | 39913934e67cab214480cc95a3632696aeb8e71a (diff) | |
download | linux-7b814900b8ccb4e61ebe704d42a12dc2d06b4a3a.tar.xz |
drm: radeon: 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: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/371172/
Signed-off-by: Christian König <christian.koenig@amd.com>
-rw-r--r-- | drivers/gpu/drm/radeon/radeon_ttm.c | 11 |
1 files changed, 5 insertions, 6 deletions
diff --git a/drivers/gpu/drm/radeon/radeon_ttm.c b/drivers/gpu/drm/radeon/radeon_ttm.c index 357e8e98cca9..f4f1e63731a5 100644 --- a/drivers/gpu/drm/radeon/radeon_ttm.c +++ b/drivers/gpu/drm/radeon/radeon_ttm.c @@ -479,7 +479,7 @@ static int radeon_ttm_tt_pin_userptr(struct ttm_tt *ttm) { struct radeon_device *rdev = radeon_get_rdev(ttm->bdev); struct radeon_ttm_tt *gtt = (void *)ttm; - unsigned pinned = 0, nents; + unsigned pinned = 0; int r; int write = !(gtt->userflags & RADEON_GEM_USERPTR_READONLY); @@ -519,9 +519,8 @@ static int radeon_ttm_tt_pin_userptr(struct ttm_tt *ttm) if (r) goto release_sg; - r = -ENOMEM; - nents = dma_map_sg(rdev->dev, ttm->sg->sgl, ttm->sg->nents, direction); - if (nents == 0) + r = dma_map_sgtable(rdev->dev, ttm->sg, direction, 0); + if (r) goto release_sg; drm_prime_sg_to_page_addr_arrays(ttm->sg, ttm->pages, @@ -552,9 +551,9 @@ static void radeon_ttm_tt_unpin_userptr(struct ttm_tt *ttm) return; /* free the sg table and pages again */ - dma_unmap_sg(rdev->dev, ttm->sg->sgl, ttm->sg->nents, direction); + dma_unmap_sgtable(rdev->dev, ttm->sg, direction, 0); - for_each_sg_page(ttm->sg->sgl, &sg_iter, ttm->sg->nents, 0) { + for_each_sgtable_page(ttm->sg, &sg_iter, 0) { struct page *page = sg_page_iter_page(&sg_iter); if (!(gtt->userflags & RADEON_GEM_USERPTR_READONLY)) set_page_dirty(page); |