Messages in this thread | | | Date | Mon, 26 Jun 2017 02:45:35 -0700 | From | Christoph Hellwig <> | Subject | Re: [PATCH v5 2/7] dma: Add simple dma_noop_mmap |
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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.
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