The Documentation/DMA-API-HOWTO.txt states that dma_map_sg returns the numer of the created entries in the DMA address space. However the subsequent calls to dma_sync_sg_for_{device,cpu} and dma_unmap_sg must be called with the original number of entries passed to dma_map_sg. The sg_table->nents in turn holds the result of the dma_map_sg call as stated in include/linux/scatterlist.h. Adapt the code to obey those rules.
Signed-off-by: Marek Szyprowski m.szyprowski@samsung.com --- For more information, see '[PATCH v2 00/21] DRM: fix struct sg_table nents vs. orig_nents misuse' thread: https://lkml.org/lkml/2020/5/4/373 --- drivers/gpu/drm/exynos/exynos_drm_g2d.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/exynos/exynos_drm_g2d.c b/drivers/gpu/drm/exynos/exynos_drm_g2d.c index fcee33a..f995b0c 100644 --- a/drivers/gpu/drm/exynos/exynos_drm_g2d.c +++ b/drivers/gpu/drm/exynos/exynos_drm_g2d.c @@ -396,7 +396,7 @@ static void g2d_userptr_put_dma_addr(struct g2d_data *g2d,
out: dma_unmap_sg(to_dma_dev(g2d->drm_dev), g2d_userptr->sgt->sgl, - g2d_userptr->sgt->nents, DMA_BIDIRECTIONAL); + g2d_userptr->sgt->orig_nents, DMA_BIDIRECTIONAL);
pages = frame_vector_pages(g2d_userptr->vec); if (!IS_ERR(pages)) { @@ -511,8 +511,9 @@ 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)) { + sgt->nents = dma_map_sg(to_dma_dev(g2d->drm_dev), sgt->sgl, + sgt->orig_nents, DMA_BIDIRECTIONAL); + if (!sgt->nents) { DRM_DEV_ERROR(g2d->dev, "failed to map sgt with dma region.\n"); ret = -ENOMEM; goto err_sg_free_table;