[PATCH v10 16/30] drm: rockchip: fix common struct sg_table related issues
From: Marek Szyprowski <m.szyprowski@samsung.com>
Date: 2020-09-04 14:12:51
Also in:
dri-devel, linux-iommu, linux-rockchip, lkml
Subsystem:
arm/rockchip soc support, drm drivers, drm drivers and misc gpu patches, drm drivers for rockchip, the rest · Maintainers:
Heiko Stuebner, David Airlie, Simona Vetter, Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann, Sandy Huang, Andy Yan, Linus Torvalds
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: Robin Murphy <robin.murphy@arm.com>
---
drivers/gpu/drm/rockchip/rockchip_drm_gem.c | 23 +++++++++------------
1 file changed, 10 insertions(+), 13 deletions(-)
diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c
index 2970e534e2bb..cb50f2ba2e46 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c@@ -36,8 +36,8 @@ static int rockchip_gem_iommu_map(struct rockchip_gem_object *rk_obj) rk_obj->dma_addr = rk_obj->mm.start; - ret = iommu_map_sg(private->domain, rk_obj->dma_addr, rk_obj->sgt->sgl, - rk_obj->sgt->nents, prot); + ret = iommu_map_sgtable(private->domain, rk_obj->dma_addr, rk_obj->sgt, + prot); if (ret < rk_obj->base.size) { DRM_ERROR("failed to map buffer: size=%zd request_size=%zd\n", ret, rk_obj->base.size);
@@ -98,11 +98,10 @@ static int rockchip_gem_get_pages(struct rockchip_gem_object *rk_obj) * TODO: Replace this by drm_clflush_sg() once it can be implemented * without relying on symbols that are not exported. */ - for_each_sg(rk_obj->sgt->sgl, s, rk_obj->sgt->nents, i) + for_each_sgtable_sg(rk_obj->sgt, s, i) sg_dma_address(s) = sg_phys(s); - dma_sync_sg_for_device(drm->dev, rk_obj->sgt->sgl, rk_obj->sgt->nents, - DMA_TO_DEVICE); + dma_sync_sgtable_for_device(drm->dev, rk_obj->sgt, DMA_TO_DEVICE); return 0;
@@ -350,8 +349,8 @@ void rockchip_gem_free_object(struct drm_gem_object *obj) if (private->domain) { rockchip_gem_iommu_unmap(rk_obj); } else { - dma_unmap_sg(drm->dev, rk_obj->sgt->sgl, - rk_obj->sgt->nents, DMA_BIDIRECTIONAL); + dma_unmap_sgtable(drm->dev, rk_obj->sgt, + DMA_BIDIRECTIONAL, 0); } drm_prime_gem_destroy(obj, rk_obj->sgt); } else {
@@ -476,15 +475,13 @@ rockchip_gem_dma_map_sg(struct drm_device *drm, struct sg_table *sg, struct rockchip_gem_object *rk_obj) { - int count = dma_map_sg(drm->dev, sg->sgl, sg->nents, - DMA_BIDIRECTIONAL); - if (!count) - return -EINVAL; + int err = dma_map_sgtable(drm->dev, sg, DMA_BIDIRECTIONAL, 0); + if (err) + return err; if (drm_prime_get_contiguous_size(sg) < attach->dmabuf->size) { DRM_ERROR("failed to map sg_table to contiguous linear address.\n"); - dma_unmap_sg(drm->dev, sg->sgl, sg->nents, - DMA_BIDIRECTIONAL); + dma_unmap_sgtable(drm->dev, sg, DMA_BIDIRECTIONAL, 0); return -EINVAL; }
--
2.17.1
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