Messages in this thread | | | Subject | Re: [PATCH dma 1/1] dma-direct: correct the physical addr in dma_direct_sync_sg_for_cpu/device | From | Robin Murphy <> | Date | Fri, 19 Jul 2019 11:38:16 +0100 |
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On 19/07/2019 10:26, fugang.duan@nxp.com wrote: > From: Fugang Duan <fugang.duan@nxp.com> > > dma_map_sg() may use swiotlb buffer when kernel parameter include > "swiotlb=force" or the dma_addr is out of dev->dma_mask range. After > DMA complete the memory moving from device to memory, then user call > dma_sync_sg_for_cpu() to sync with DMA buffer, and copy the original > virtual buffer to other space. > > So dma_direct_sync_sg_for_cpu() should use swiotlb physical addr, not > the original physical addr from sg_phys(sg). > > dma_direct_sync_sg_for_device() also has the similar issue, correct it.
Yikes, that was unfortunate. There aren't too many users of dma_sync_sg*(), but I note that a few of them are in and around v4l2, so this could well explain the video brokenness that Al reported.
AFAICS the fix looks appropriate;
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
> Fixes: 55897af63091("dma-direct: merge swiotlb_dma_ops into the dma_direct code") > Signed-off-by: Fugang Duan <fugang.duan@nxp.com> > --- > kernel/dma/direct.c | 18 +++++++++++------- > 1 file changed, 11 insertions(+), 7 deletions(-) > > diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c > index b90e1ae..0e87f86 100644 > --- a/kernel/dma/direct.c > +++ b/kernel/dma/direct.c > @@ -242,12 +242,14 @@ void dma_direct_sync_sg_for_device(struct device *dev, > int i; > > for_each_sg(sgl, sg, nents, i) { > - if (unlikely(is_swiotlb_buffer(sg_phys(sg)))) > - swiotlb_tbl_sync_single(dev, sg_phys(sg), sg->length, > + phys_addr_t paddr = dma_to_phys(dev, sg_dma_address(sg)); > + > + if (unlikely(is_swiotlb_buffer(paddr))) > + swiotlb_tbl_sync_single(dev, paddr, sg->length, > dir, SYNC_FOR_DEVICE); > > if (!dev_is_dma_coherent(dev)) > - arch_sync_dma_for_device(dev, sg_phys(sg), sg->length, > + arch_sync_dma_for_device(dev, paddr, sg->length, > dir); > } > } > @@ -279,11 +281,13 @@ void dma_direct_sync_sg_for_cpu(struct device *dev, > int i; > > for_each_sg(sgl, sg, nents, i) { > + phys_addr_t paddr = dma_to_phys(dev, sg_dma_address(sg)); > + > if (!dev_is_dma_coherent(dev)) > - arch_sync_dma_for_cpu(dev, sg_phys(sg), sg->length, dir); > - > - if (unlikely(is_swiotlb_buffer(sg_phys(sg)))) > - swiotlb_tbl_sync_single(dev, sg_phys(sg), sg->length, dir, > + arch_sync_dma_for_cpu(dev, paddr, sg->length, dir); > + > + if (unlikely(is_swiotlb_buffer(paddr))) > + swiotlb_tbl_sync_single(dev, paddr, sg->length, dir, > SYNC_FOR_CPU); > } > >
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