linux-kernel - Re: [PATCH v5] spi: spi-ti-qspi: Add DMA support for QSPI mmap read

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Message-ID: <20160816184253.GC9347@sirena.org.uk>
Date:	Tue, 16 Aug 2016 19:42:53 +0100
From:	Mark Brown <broonie@...nel.org>
To:	Vignesh R <vigneshr@...com>
Cc:	linux-spi@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-omap@...r.kernel.org
Subject: Re: [PATCH v5] spi: spi-ti-qspi: Add DMA support for QSPI mmap read

On Tue, Aug 09, 2016 at 06:20:01PM +0530, Vignesh R wrote:
> 
> 

> According to this thread[1], converting virtual address
> pointer into scatterlist which is then DMA mapped is unsafe on systems
> with certain cache architecture. Hence, I added code to handle kmap
> buffers inside the driver rather than updating generic spi-core code.

That's saying that things that aren't covered aren't DMAable safely at
all which is a more general issue...

> If its okay to update the spi_map_buf() to handle kmap buffers as above
> then I can submit the patch accordingly.

Yes, the whole point is that this is all in generic code so drivers
don't need to worry about it.

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