diff options
| author | Marek Szyprowski <m.szyprowski@samsung.com> | 2020-04-28 13:09:11 +0200 |
|---|---|---|
| committer | Marek Szyprowski <m.szyprowski@samsung.com> | 2020-09-10 08:18:35 +0200 |
| commit | c3d9c17f486d5c54940487dc31a54ebfdeeb371a (patch) | |
| tree | 3ee53991d4a974a68f46ffcfd187caa6365b9bed /drivers/gpu/drm/lima/lima_vm.c | |
| parent | b827e3ac4185a6091b90263b6516b54a766c109e (diff) | |
drm: lima: 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: Qiang Yu <yuq825@gmail.com>
Diffstat (limited to 'drivers/gpu/drm/lima/lima_vm.c')
| -rw-r--r-- | drivers/gpu/drm/lima/lima_vm.c | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/drivers/gpu/drm/lima/lima_vm.c b/drivers/gpu/drm/lima/lima_vm.c index 5b92fb82674a..2b2739adc7f5 100644 --- a/drivers/gpu/drm/lima/lima_vm.c +++ b/drivers/gpu/drm/lima/lima_vm.c @@ -124,7 +124,7 @@ int lima_vm_bo_add(struct lima_vm *vm, struct lima_bo *bo, bool create) if (err) goto err_out1; - for_each_sg_dma_page(bo->base.sgt->sgl, &sg_iter, bo->base.sgt->nents, 0) { + for_each_sgtable_dma_page(bo->base.sgt, &sg_iter, 0) { err = lima_vm_map_page(vm, sg_page_iter_dma_address(&sg_iter), bo_va->node.start + offset); if (err) @@ -298,8 +298,7 @@ int lima_vm_map_bo(struct lima_vm *vm, struct lima_bo *bo, int pageoff) mutex_lock(&vm->lock); base = bo_va->node.start + (pageoff << PAGE_SHIFT); - for_each_sg_dma_page(bo->base.sgt->sgl, &sg_iter, - bo->base.sgt->nents, pageoff) { + for_each_sgtable_dma_page(bo->base.sgt, &sg_iter, pageoff) { err = lima_vm_map_page(vm, sg_page_iter_dma_address(&sg_iter), base + offset); if (err) |