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Date:   Fri, 23 Jul 2021 18:44:04 +0100
From:   Jonathan Cameron <Jonathan.Cameron@Huawei.com>
To:     Mark Brown <broonie@kernel.org>
CC:     Puranjay Mohan <puranjay12@gmail.com>,
        <Michael.Hennerich@analog.com>, <alexandru.ardelean@analog.com>,
        <jic23@kernel.org>, <devicetree@vger.kernel.org>,
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        <lars@metafoo.de>, <Dragos.Bogdan@analog.com>,
        <Darius.Berghe@analog.com>
Subject: Re: [PATCH v2 2/2] iio: accel: Add driver support for ADXL355
Message-ID: <20210723184404.0000001d@Huawei.com>
In-Reply-To: <20210723171422.GK5221@sirena.org.uk>
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        <20210722062155.32998-3-puranjay12@gmail.com>
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On Fri, 23 Jul 2021 18:14:22 +0100
Mark Brown <broonie@kernel.org> wrote:

> On Fri, Jul 23, 2021 at 06:10:22PM +0100, Jonathan Cameron wrote:
> 
> > @Mark.  This has come up a few times recently.  Are we now safe to assume
> > that regmap will always copy data when used with SPI and hence we no
> > longer need to ensure DMA safe buffers?     
> 
> Only for single register I/O, I'd not assume that for things like raw
> I/O.

Thanks for the confirmation.  So in this driver that means we
need DMA safe buffers for the regmap_bulk_ calls.  Easiest approach
is probably to use a __cacheline_aligned buffer at the end of the
iio_priv() structure.

> 
> Note that my name is spelt Mark.
> 

I'll blame Friday.

Thanks,

Jonathan