| From cbf09081da232a9d06bf0f27dcdf9cd73465fb91 Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Tue, 28 Apr 2020 13:08:41 +0200 |
| Subject: drm: exynos: fix common struct sg_table related issues |
| |
| From: Marek Szyprowski <m.szyprowski@samsung.com> |
| |
| [ 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@samsung.com> |
| Reviewed-by: Andrzej Hajda <a.hajda@samsung.com> |
| Acked-by : Inki Dae <inki.dae@samsung.com> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| drivers/gpu/drm/exynos/exynos_drm_g2d.c | 10 +++++----- |
| 1 file changed, 5 insertions(+), 5 deletions(-) |
| |
| 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; |
| } |
| |
| -- |
| 2.27.0 |
| |