From: Christoph Hellwig <hch@lst•de>
To: Gavin Li <gavinli@thegavinli•com>
Cc: Gavin Li <git@thegavinli•com>, Shawn Anastasio <shawn@anastas•io>,
Michael Ellerman <mpe@ellerman•id.au>,
linuxppc-dev@lists•ozlabs.org, linux-kernel@vger•kernel.org,
Russell King <linux@armlinux•org.uk>,
linux-mips@vger•kernel.org, Paul Burton <paul.burton@mips•com>,
Catalin Marinas <catalin.marinas@arm•com>,
James Hogan <jhogan@kernel•org>, Will Deacon <will@kernel•org>,
Christoph Hellwig <hch@lst•de>,
linux-arm-kernel@lists•infradead.org,
Robin Murphy <robin.murphy@arm•com>
Subject: Re: [PATCH 1/2] dma-mapping: fix page attributes for dma_mmap_*
Date: Tue, 6 Aug 2019 07:12:42 +0200 [thread overview]
Message-ID: <20190806051242.GA13269@lst.de> (raw)
In-Reply-To: <CA+GxvY5C_rrukCzC5K-h72bePyW8PS_Rfj3uxh-K6UrcAextUQ@mail.gmail.com>
On Mon, Aug 05, 2019 at 07:55:44PM -0700, Gavin Li wrote:
> > /* create a coherent mapping */
> > ret = dma_common_contiguous_remap(page, size, VM_USERMAP,
> > - arch_dma_mmap_pgprot(dev, PAGE_KERNEL, attrs),
> > + dma_pgprot(dev, PAGE_KERNEL, attrs),
> > __builtin_return_address(0));
> > if (!ret) {
> > __dma_direct_free_pages(dev, size, page);
>
> Is dma_common_contiguous_remap() still necessary in the
> DMA_ATTR_NON_CONSISTENT case? I would presume it would be fine to just
> return a linearly mapped address in that case.
It would not be required for a real DMA_ATTR_NON_CONSISTENT
implementation. But only parisc and mips actually properly implement
DMA_ATTR_NON_CONSISTENT, everyone ignores it. Given that the API is
a little ill defined and I have a better replacement in the pipeline
I don't want to start implementing it for other architectures now.
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next prev parent reply other threads:[~2019-08-06 5:13 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-05 8:01 fix default dma_mmap_* pgprot v2 Christoph Hellwig
2019-08-05 8:01 ` [PATCH 1/2] dma-mapping: fix page attributes for dma_mmap_* Christoph Hellwig
2019-08-05 9:10 ` Catalin Marinas
[not found] ` <CAP_+7SzPdNCMKuuXMjHjpCzxsey2YWR_e6mTAWtNSZ6kKBvKFw@mail.gmail.com>
2019-08-06 2:55 ` Gavin Li
2019-08-06 5:12 ` Christoph Hellwig [this message]
2019-08-06 19:39 ` Shawn Anastasio
2019-08-07 6:04 ` Christoph Hellwig
2019-08-07 11:45 ` Shawn Anastasio
2019-08-05 8:01 ` [PATCH 2/2] MIPS: remove support for DMA_ATTR_WRITE_COMBINE Christoph Hellwig
2019-08-05 8:06 ` Sergei Shtylyov
-- strict thread matches above, loose matches on Subject: below --
2019-08-07 6:16 fix default dma_mmap_* pgprot v3 Christoph Hellwig
2019-08-07 6:16 ` [PATCH 1/2] dma-mapping: fix page attributes for dma_mmap_* Christoph Hellwig
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