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From: Shawn Anastasio <shawn@anastas.io>
To: Christoph Hellwig <hch@lst.de>, iommu@lists.linux-foundation.org
Cc: Michael Ellerman <mpe@ellerman.id.au>,
	Russell King <linux@armlinux.org.uk>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	Robin Murphy <robin.murphy@arm.com>,
	Paul Burton <paul.burton@mips.com>,
	James Hogan <jhogan@kernel.org>,
	linuxppc-dev@lists.ozlabs.org, linux-mips@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, Gavin Li <git@thegavinli.com>
Subject: Re: [PATCH 1/2] dma-mapping: fix page attributes for dma_mmap_*
Date: Tue, 6 Aug 2019 21:39:06 +0200	[thread overview]
Message-ID: <7df95ffb-6df3-b118-284c-ee32cad81199@anastas.io> (raw)
In-Reply-To: <20190805080145.5694-2-hch@lst.de>

On 8/5/19 10:01 AM, Christoph Hellwig wrote:
> diff --git a/include/linux/dma-noncoherent.h b/include/linux/dma-noncoherent.h
> index 3813211a9aad..9ae5cee543c4 100644
> --- a/include/linux/dma-noncoherent.h
> +++ b/include/linux/dma-noncoherent.h
> @@ -42,13 +42,8 @@ void arch_dma_free(struct device *dev, size_t size, void *cpu_addr,
>   		dma_addr_t dma_addr, unsigned long attrs);
>   long arch_dma_coherent_to_pfn(struct device *dev, void *cpu_addr,
>   		dma_addr_t dma_addr);
> -
> -#ifdef CONFIG_ARCH_HAS_DMA_MMAP_PGPROT
>   pgprot_t arch_dma_mmap_pgprot(struct device *dev, pgprot_t prot,
>   		unsigned long attrs);
> -#else
> -# define arch_dma_mmap_pgprot(dev, prot, attrs)	pgprot_noncached(prot)
> -#endif

Nit, but maybe the prototype should still be ifdef'd here? It at least
could prevent a reader from incorrectly thinking that the function is
always present.

Also, like Will mentioned earlier, the function name isn't entirely
accurate anymore. I second the suggestion of using something like
arch_dma_noncoherent_pgprot(). As for your idea of defining
pgprot_dmacoherent for all architectures as

#ifndef pgprot_dmacoherent
#define pgprot_dmacoherent pgprot_noncached
#endif

I think that the name here is kind of misleading too, since this
definition will only be used when there is no support for proper
DMA coherency.


  parent reply	other threads:[~2019-08-06 19:47 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
2019-08-06 19:39   ` Shawn Anastasio [this message]
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
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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