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Message-Id: <20200504125359.5678-17-m.szyprowski@samsung.com>
Date: Mon, 4 May 2020 14:53:55 +0200
From: Marek Szyprowski <m.szyprowski@...sung.com>
To: dri-devel@...ts.freedesktop.org, iommu@...ts.linux-foundation.org,
linaro-mm-sig@...ts.linaro.org, linux-kernel@...r.kernel.org
Cc: Marek Szyprowski <m.szyprowski@...sung.com>,
Christoph Hellwig <hch@....de>,
Robin Murphy <robin.murphy@....com>,
Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
linux-arm-kernel@...ts.infradead.org,
David Airlie <airlied@...ux.ie>,
Daniel Vetter <daniel@...ll.ch>,
Laurent Pinchart <laurent.pinchart@...asonboard.com>,
Kieran Bingham <kieran.bingham+renesas@...asonboard.com>,
Mauro Carvalho Chehab <mchehab@...nel.org>,
linux-media@...r.kernel.org, linux-renesas-soc@...r.kernel.org
Subject: [PATCH v2 17/21] drm: rcar-du: fix sg_table nents vs. orig_nents
misuse
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@...sung.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/media/platform/vsp1/vsp1_drm.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/media/platform/vsp1/vsp1_drm.c b/drivers/media/platform/vsp1/vsp1_drm.c
index a4a45d6..b54a30f 100644
--- a/drivers/media/platform/vsp1/vsp1_drm.c
+++ b/drivers/media/platform/vsp1/vsp1_drm.c
@@ -912,8 +912,9 @@ int vsp1_du_map_sg(struct device *dev, struct sg_table *sgt)
* skip cache sync. This will need to be revisited when support for
* non-coherent buffers will be added to the DU driver.
*/
- return dma_map_sg_attrs(vsp1->bus_master, sgt->sgl, sgt->nents,
- DMA_TO_DEVICE, DMA_ATTR_SKIP_CPU_SYNC);
+ sgt->nents = dma_map_sg_attrs(vsp1->bus_master, sgt->sgl,
+ sgt->orig_nents, DMA_TO_DEVICE, DMA_ATTR_SKIP_CPU_SYNC);
+ return sgt->nents;
}
EXPORT_SYMBOL_GPL(vsp1_du_map_sg);
@@ -921,7 +922,7 @@ void vsp1_du_unmap_sg(struct device *dev, struct sg_table *sgt)
{
struct vsp1_device *vsp1 = dev_get_drvdata(dev);
- dma_unmap_sg_attrs(vsp1->bus_master, sgt->sgl, sgt->nents,
+ dma_unmap_sg_attrs(vsp1->bus_master, sgt->sgl, sgt->orig_nents,
DMA_TO_DEVICE, DMA_ATTR_SKIP_CPU_SYNC);
}
EXPORT_SYMBOL_GPL(vsp1_du_unmap_sg);
--
1.9.1
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