Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Fri, 23 Jul 2021 18:47:51 +0100
From:   Mark Brown <broonie@kernel.org>
To:     Jonathan Cameron <Jonathan.Cameron@Huawei.com>
Cc:     Puranjay Mohan <puranjay12@gmail.com>,
        Michael.Hennerich@analog.com, alexandru.ardelean@analog.com,
        jic23@kernel.org, devicetree@vger.kernel.org,
        linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org,
        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: <20210723174751.GL5221@sirena.org.uk>
References: <20210723184404.0000001d@Huawei.com>
MIME-Version: 1.0
Content-Type: multipart/signed; micalg=pgp-sha512;
        protocol="application/pgp-signature"; boundary="rfwNdt5cNUUjB/69"
Content-Disposition: inline
In-Reply-To: <20210723184404.0000001d@Huawei.com>
User-Agent: Mutt/1.10.1 (2018-07-13)
Precedence: bulk


--rfwNdt5cNUUjB/69
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable

On Fri, Jul 23, 2021 at 06:44:04PM +0100, Jonathan Cameron wrote:
> Mark Brown <broonie@kernel.org> wrote:

> > > @Mark.  This has come up a few times recently.  Are we now safe to as=
sume
> > > that regmap will always copy data when used with SPI and hence we no
> > > longer need to ensure DMA safe buffers?    =20

> > 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.

Yeah, it might be fine depending on the bus/format type but it's not
something you can generally assume.

--rfwNdt5cNUUjB/69
Content-Type: application/pgp-signature; name="signature.asc"

-----BEGIN PGP SIGNATURE-----

iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAmD7AMcACgkQJNaLcl1U
h9CP+Qf+Lsc5GFkzeUzJpgvTvqmz/f+mVquFladiTHzq4Vd4lCSrD+l12g2lHQHQ
bOgOkoGRi0M/NOCwetKglIQNwyUY8WtGY+I8GNpZL53wN//EjBVF29EyM6/huRxt
W+tzv2euWk9Tzq6wKj9P8G7Sa0/kIune3KaxtXA8bmEheJ0OszZBLV3qkY3PYgTF
8GWsGQCGkysrve98sTfQcjWyFsPNFgKhMsBQ6SPYYebK8xtFy9qIezumGkXuWQBw
k0PFc9Lwz+X/ownmafloKIzZCmHkbpL87h+SBI6HS7BN6kLWFe1aVzuGDaqJy9HN
e64jWE5y4GtlufUNHTpbWH7cfXLeMg==
=PJ6s
-----END PGP SIGNATURE-----

--rfwNdt5cNUUjB/69--