From 34a4e66faf8b22c8409cbd46839ba5e488b1e6a9 Mon Sep 17 00:00:00 2001 From: Marek Szyprowski Date: Tue, 28 Apr 2020 13:09:35 +0200 Subject: drm: panfrost: 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. 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 Reviewed-by: Steven Price Reviewed-by: Rob Herring --- drivers/gpu/drm/panfrost/panfrost_mmu.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) (limited to 'drivers/gpu/drm/panfrost/panfrost_mmu.c') diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.c b/drivers/gpu/drm/panfrost/panfrost_mmu.c index e8f7b11352d2..776448c527ea 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); -- cgit