From: Christoph Hellwig <hch@infradead.org>
To: Vladimir Murzin <vladimir.murzin@arm.com>
Cc: Christoph Hellwig <hch@infradead.org>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux@armlinux.org.uk, sza@esh.hu,
arnd@arndb.de, gregkh@linuxfoundation.org,
akpm@linux-foundation.org, alexandre.torgue@st.com,
robin.murphy@arm.com, benjamin.gaignard@linaro.org,
kbuild-all@01.org, Joerg Roedel <jroedel@suse.de>,
Christian Borntraeger <borntraeger@de.ibm.com>
Subject: Re: [PATCH v5 2/7] dma: Add simple dma_noop_mmap
Date: Mon, 26 Jun 2017 02:45:35 -0700 [thread overview]
Message-ID: <20170626094535.GD21570@infradead.org> (raw)
In-Reply-To: <8670225a-30a5-d567-0979-c96fd115a50f@arm.com>
On Thu, Jun 22, 2017 at 01:46:09PM +0100, Vladimir Murzin wrote:
> On 20/06/17 14:23, Christoph Hellwig wrote:
> > On Wed, May 24, 2017 at 11:24:27AM +0100, Vladimir Murzin wrote:
> >> This patch adds a simple implementation of mmap to dma_noop_ops.
> >
> > Currently we use dma_common_mmap as the generic fallback if a dma_ops
> > instance doesn't implement a mmap method. Can you just fix up
> > dma_common_mmap for your nommu case - it looks like yours is basically
> > a subset.
>
> dma_common_map() is guarded with CONFIG_MMU and I'm not dare to change that
> since I have no idea 1) why it was done 2) how it affects other arches :(
That's still not a good reason for duplicating it. Please instead
make all the existing nommu architecture select
CONFIG_ARCH_NO_COHERENT_DMA_MMAP as a prep patch, then provide an
arch helper to abstract away the pgprot_noncached, then lift
CONFIG_ARCH_NO_COHERENT_DMA_MMAP for arm nommu. Bonus points
for lifting it elsewhere or consolidating various copy & paste
versions of the function.
next prev parent reply other threads:[~2017-06-26 9:45 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-24 10:24 [PATCH v5 0/7] ARM: Fix dma_alloc_coherent() and friends for NOMMU Vladimir Murzin
2017-05-24 10:24 ` [PATCH v5 1/7] dma: Take into account dma_pfn_offset Vladimir Murzin
2017-06-20 13:24 ` Christoph Hellwig
2017-06-22 12:47 ` Vladimir Murzin
2017-05-24 10:24 ` [PATCH v5 2/7] dma: Add simple dma_noop_mmap Vladimir Murzin
2017-06-20 13:23 ` Christoph Hellwig
2017-06-22 12:46 ` Vladimir Murzin
2017-06-26 9:45 ` Christoph Hellwig [this message]
2017-05-24 10:24 ` [PATCH v5 3/7] drivers: dma-coherent: Account dma_pfn_offset when used with device tree Vladimir Murzin
2017-06-20 13:42 ` Christoph Hellwig
2017-06-20 13:50 ` Robin Murphy
2017-06-26 9:37 ` Christoph Hellwig
2017-06-22 12:59 ` Vladimir Murzin
2017-05-24 10:24 ` [PATCH v5 4/7] drivers: dma-coherent: Introduce default DMA pool Vladimir Murzin
2017-06-20 13:49 ` Christoph Hellwig
2017-06-20 14:24 ` Robin Murphy
2017-06-26 9:42 ` Christoph Hellwig
2017-06-26 14:08 ` Vladimir Murzin
2017-06-27 14:36 ` Robin Murphy
2017-06-27 15:22 ` Christoph Hellwig
2017-06-22 13:18 ` Vladimir Murzin
2017-06-26 9:44 ` Christoph Hellwig
2017-05-24 10:24 ` [PATCH v5 5/7] ARM: NOMMU: Introduce dma operations for noMMU Vladimir Murzin
2017-05-24 10:24 ` [PATCH v5 6/7] ARM: NOMMU: Set ARM_DMA_MEM_BUFFERABLE for M-class cpus Vladimir Murzin
2017-05-24 10:24 ` [PATCH v5 7/7] ARM: dma-mapping: Remove traces of NOMMU code Vladimir Murzin
2017-06-08 8:28 ` [PATCH v5 0/7] ARM: Fix dma_alloc_coherent() and friends for NOMMU Vladimir Murzin
2017-06-08 16:25 ` Russell King - ARM Linux
2017-06-15 7:25 ` Vladimir Murzin
2017-06-20 12:59 ` Vladimir Murzin
2017-06-20 13:00 ` Christoph Hellwig
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