From: Christoph Hellwig <hch@lst.de>
To: Thierry Reding <thierry.reding@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>,
Marek Szyprowski <m.szyprowski@samsung.com>,
Robin Murphy <robin.murphy@arm.com>,
iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] dma-direct: Export dma_direct_alloc() and dma_direct_free()
Date: Tue, 5 Feb 2019 17:38:37 +0100 [thread overview]
Message-ID: <20190205163837.GA1222@lst.de> (raw)
In-Reply-To: <20190205162057.GA29974@ulmo>
On Tue, Feb 05, 2019 at 05:20:57PM +0100, Thierry Reding wrote:
> The problem is that if I use dma_alloc_coherent(), then the memory will
> already be mapped via the SMMU at that point and then the driver, not
> knowing that memory has already been mapped, will attempt to map an IOVA
> which will cause an SMMU fault when the host1x tries to access the
> memory.
>
> I didn't find an equivalent to arm_iommu_detach_device() for non-ARM,
> but then stumbled across this and thought it was rather convenient for
> these cases. If there's a better way to deal with this situation, I'd be
> happy to do so.
So you basically do a dma_direct_alloc + iommu_map? Can you send me
a pointer to your code? Maybe we need to add a proper IOMMU-layer
API for that.
next prev parent reply other threads:[~2019-02-05 16:38 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-05 11:06 [PATCH] dma-direct: Export dma_direct_alloc() and dma_direct_free() Thierry Reding
2019-02-05 16:10 ` Christoph Hellwig
2019-02-05 16:20 ` Thierry Reding
2019-02-05 16:38 ` Christoph Hellwig [this message]
2019-02-05 17:56 ` Thierry Reding
2019-02-05 18:02 ` Christoph Hellwig
2019-02-05 22:29 ` Thierry Reding
2019-02-06 6:57 ` Christoph Hellwig
2019-02-06 7:37 ` Marek Szyprowski
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