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SubjectRe: [PATCH] ARM: dma-mapping: Clear DMA ops on teardown
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Hi Robin,

On 2019-01-21 15:52, Robin Murphy wrote:
> Installing the appropriate non-IOMMU DMA ops in arm_iommu_detch_device()
> serves the case where IOMMU-aware drivers choose to control their own
> mapping but still make DMA API calls, however it also affects the case
> when the arch code itself tears down the mapping upon driver unbinding,
> where the ops now get left in place and can inhibit arch_setup_dma_ops()
> on subsequent re-probe attempts.
>
> Fix the latter case by making sure that arch_teardown_dma_ops() cleans
> up whenever the ops were automatically installed by its counterpart.
>
> Reported-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
> Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
> Fixes: 1874619a7df4 "ARM: dma-mapping: Set proper DMA ops in arm_iommu_detach_device()"
> Tested-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
> ---
>
> Sorry for the delay - there was a giant email infrastructure cock-up just
> at the point I wanted to go back through my archive and double-check the
> discussion around the original commit...

No problem, could you also upload it to rmk's patch tracking system?
IMHO rmk's tree will be the best place to handle this fix.

> Robin.
>
> arch/arm/mm/dma-mapping.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
> index f1e2922e447c..1e3e08a1c456 100644
> --- a/arch/arm/mm/dma-mapping.c
> +++ b/arch/arm/mm/dma-mapping.c
> @@ -2390,4 +2390,6 @@ void arch_teardown_dma_ops(struct device *dev)
> return;
>
> arm_teardown_iommu_dma_ops(dev);
> + /* Let arch_setup_dma_ops() start again from scratch upon re-probe */
> + set_dma_ops(dev, NULL);
> }

Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland

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