| From c21d6d333424f049606dcc2eb6ed9c03cc77a1d1 Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Tue, 28 Apr 2020 13:09:35 +0200 |
| Subject: drm: panfrost: fix common struct sg_table related issues |
| |
| From: Marek Szyprowski <m.szyprowski@samsung.com> |
| |
| [ Upstream commit 34a4e66faf8b22c8409cbd46839ba5e488b1e6a9 ] |
| |
| 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: Steven Price <steven.price@arm.com> |
| Reviewed-by: Rob Herring <robh@kernel.org> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| drivers/gpu/drm/panfrost/panfrost_gem.c | 4 ++-- |
| drivers/gpu/drm/panfrost/panfrost_mmu.c | 7 +++---- |
| 2 files changed, 5 insertions(+), 6 deletions(-) |
| |
| diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.c b/drivers/gpu/drm/panfrost/panfrost_gem.c |
| index 33355dd302f11..1a6cea0e0bd74 100644 |
| --- a/drivers/gpu/drm/panfrost/panfrost_gem.c |
| +++ b/drivers/gpu/drm/panfrost/panfrost_gem.c |
| @@ -41,8 +41,8 @@ static void panfrost_gem_free_object(struct drm_gem_object *obj) |
| |
| for (i = 0; i < n_sgt; i++) { |
| if (bo->sgts[i].sgl) { |
| - dma_unmap_sg(pfdev->dev, bo->sgts[i].sgl, |
| - bo->sgts[i].nents, DMA_BIDIRECTIONAL); |
| + dma_unmap_sgtable(pfdev->dev, &bo->sgts[i], |
| + DMA_BIDIRECTIONAL, 0); |
| sg_free_table(&bo->sgts[i]); |
| } |
| } |
| diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.c b/drivers/gpu/drm/panfrost/panfrost_mmu.c |
| index e8f7b11352d27..776448c527ea9 100644 |
| --- a/drivers/gpu/drm/panfrost/panfrost_mmu.c |
| +++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c |
| @@ -253,7 +253,7 @@ static int mmu_map_sg(struct panfrost_device *pfdev, struct panfrost_mmu *mmu, |
| struct io_pgtable_ops *ops = mmu->pgtbl_ops; |
| u64 start_iova = iova; |
| |
| - for_each_sg(sgt->sgl, sgl, sgt->nents, count) { |
| + for_each_sgtable_dma_sg(sgt, sgl, count) { |
| unsigned long paddr = sg_dma_address(sgl); |
| size_t len = sg_dma_len(sgl); |
| |
| @@ -517,10 +517,9 @@ static int panfrost_mmu_map_fault_addr(struct panfrost_device *pfdev, int as, |
| if (ret) |
| goto err_pages; |
| |
| - if (!dma_map_sg(pfdev->dev, sgt->sgl, sgt->nents, DMA_BIDIRECTIONAL)) { |
| - ret = -EINVAL; |
| + ret = dma_map_sgtable(pfdev->dev, sgt, DMA_BIDIRECTIONAL, 0); |
| + if (ret) |
| goto err_map; |
| - } |
| |
| mmu_map_sg(pfdev, bomapping->mmu, addr, |
| IOMMU_WRITE | IOMMU_READ | IOMMU_NOEXEC, sgt); |
| -- |
| 2.27.0 |
| |