diff options
| author | Marek Szyprowski <m.szyprowski@samsung.com> | 2020-04-28 13:10:45 +0200 |
|---|---|---|
| committer | Marek Szyprowski <m.szyprowski@samsung.com> | 2020-09-10 08:18:35 +0200 |
| commit | 5e0ff16b9edf3379e5a0e1545b0d9831a7353cca (patch) | |
| tree | 3e40c0cd83732a1049ad29f9f4a8d2071d813b9f /drivers/gpu/drm/xen | |
| parent | c915c2cbaf5eb256d26f40cfce1c5defbfcadab9 (diff) | |
| download | linux-5e0ff16b9edf3379e5a0e1545b0d9831a7353cca.tar.bz2 | |
drm: xen: 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.
Fix the code to refer to proper nents or orig_nents entries. This driver
reports the number of the pages in the imported scatterlist, so it should
refer to sg_table->orig_nents entry.
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Diffstat (limited to 'drivers/gpu/drm/xen')
| -rw-r--r-- | drivers/gpu/drm/xen/xen_drm_front_gem.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/gpu/drm/xen/xen_drm_front_gem.c b/drivers/gpu/drm/xen/xen_drm_front_gem.c index 39ff95b75357..0e57c80058b2 100644 --- a/drivers/gpu/drm/xen/xen_drm_front_gem.c +++ b/drivers/gpu/drm/xen/xen_drm_front_gem.c @@ -216,7 +216,7 @@ xen_drm_front_gem_import_sg_table(struct drm_device *dev, return ERR_PTR(ret); DRM_DEBUG("Imported buffer of size %zu with nents %u\n", - size, sgt->nents); + size, sgt->orig_nents); return &xen_obj->base; } |