This is a note to let you know that I've just added the patch titled
drm: exynos: fix common struct sg_table related issues
to the 5.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-exynos-fix-common-struct-sg_table-related-issues.patch
and it can be found in the queue-5.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit cbf09081da232a9d06bf0f27dcdf9cd73465fb91
Author: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Date: Tue Apr 28 13:08:41 2020 +0200
drm: exynos: fix common struct sg_table related issues
[ Upstream commit 84404614167b829f7b58189cd24b6c0c74897171 ]
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@xxxxxxxxxxx>
Reviewed-by: Andrzej Hajda <a.hajda@xxxxxxxxxxx>
Acked-by : Inki Dae <inki.dae@xxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/gpu/drm/exynos/exynos_drm_g2d.c b/drivers/gpu/drm/exynos/exynos_drm_g2d.c
index 03be314271811..967a5cdc120e3 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_g2d.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_g2d.c
@@ -395,8 +395,8 @@ static void g2d_userptr_put_dma_addr(struct g2d_data *g2d,
return;
out:
- dma_unmap_sg(to_dma_dev(g2d->drm_dev), g2d_userptr->sgt->sgl,
- g2d_userptr->sgt->nents, DMA_BIDIRECTIONAL);
+ dma_unmap_sgtable(to_dma_dev(g2d->drm_dev), g2d_userptr->sgt,
+ DMA_BIDIRECTIONAL, 0);
pages = frame_vector_pages(g2d_userptr->vec);
if (!IS_ERR(pages)) {
@@ -511,10 +511,10 @@ static dma_addr_t *g2d_userptr_get_dma_addr(struct g2d_data *g2d,
g2d_userptr->sgt = sgt;
- if (!dma_map_sg(to_dma_dev(g2d->drm_dev), sgt->sgl, sgt->nents,
- DMA_BIDIRECTIONAL)) {
+ ret = dma_map_sgtable(to_dma_dev(g2d->drm_dev), sgt,
+ DMA_BIDIRECTIONAL, 0);
+ if (ret) {
DRM_DEV_ERROR(g2d->dev, "failed to map sgt with dma region.\n");
- ret = -ENOMEM;
goto err_sg_free_table;
}
