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Date:   Mon, 4 Dec 2023 16:51:29 +0000
From:   Jonathan Cameron <jic23@kernel.org>
To:     Nuno =?UTF-8?B?U8Oh?= <noname.nuno@gmail.com>
Cc:     Nuno Sa via B4 Relay <devnull+nuno.sa.analog.com@kernel.org>,
        nuno.sa@analog.com, linux-kernel@vger.kernel.org,
        devicetree@vger.kernel.org, linux-iio@vger.kernel.org,
        Olivier MOYSAN <olivier.moysan@foss.st.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Frank Rowand <frowand.list@gmail.com>,
        Lars-Peter Clausen <lars@metafoo.de>,
        Michael Hennerich <Michael.Hennerich@analog.com>
Subject: Re: [PATCH 06/12] iio: adc: ad9467: add mutex to struct
 ad9467_state
Message-ID: <20231204165129.130e189c@jic23-huawei>
In-Reply-To: <69a7ca77055fc57cff6d6be95fb5796723171230.camel@gmail.com>
References: <20231121-dev-iio-backend-v1-0-6a3d542eba35@analog.com>
        <20231121-dev-iio-backend-v1-6-6a3d542eba35@analog.com>
        <20231204152301.6c212539@jic23-huawei>
        <69a7ca77055fc57cff6d6be95fb5796723171230.camel@gmail.com>
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On Mon, 04 Dec 2023 17:10:01 +0100
Nuno S=C3=A1 <noname.nuno@gmail.com> wrote:

> On Mon, 2023-12-04 at 15:23 +0000, Jonathan Cameron wrote:
> > On Tue, 21 Nov 2023 11:20:19 +0100
> > Nuno Sa via B4 Relay <devnull+nuno.sa.analog.com@kernel.org> wrote:
> >  =20
> > > From: Nuno Sa <nuno.sa@analog.com>
> > >=20
> > > When calling ad9467_set_scale(), multiple calls to ad9467_spi_write()
> > > are done which means we need to properly protect the whole operation =
so
> > > we are sure we will be in a sane state if two concurrent calls occur.
> > >=20
> > > Fixes: ad6797120238 ("iio: adc: ad9467: add support AD9467 ADC")
> > > Signed-off-by: Nuno Sa <nuno.sa@analog.com>
> > > ---
> > > =C2=A0drivers/iio/adc/ad9467.c | 6 +++++-
> > > =C2=A01 file changed, 5 insertions(+), 1 deletion(-)
> > >=20
> > > diff --git a/drivers/iio/adc/ad9467.c b/drivers/iio/adc/ad9467.c
> > > index 04474dbfa631..91821dee03b7 100644
> > > --- a/drivers/iio/adc/ad9467.c
> > > +++ b/drivers/iio/adc/ad9467.c
> > > @@ -4,7 +4,7 @@
> > > =C2=A0 *
> > > =C2=A0 * Copyright 2012-2020 Analog Devices Inc.
> > > =C2=A0 */
> > > -
> > > +#include <linux/cleanup.h>
> > > =C2=A0#include <linux/module.h>
> > > =C2=A0#include <linux/mutex.h>
> > > =C2=A0#include <linux/device.h>
> > > @@ -122,6 +122,8 @@ struct ad9467_state {
> > > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0unsigned int=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0output_mode;
> > > =C2=A0
> > > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0struct gpio_desc=C2=
=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0*pwrdown_gpio;
> > > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0/* protect against concurr=
ent accesses to the device */ =20
> > Not very specific.=C2=A0 Concurrent access usually fine at granularity =
of
> > individual read/write as the bus locks protect it.=C2=A0 What state
> > is actually being protected?=C2=A0 A shared buffer or some state that we
> > need to ensure remains consistent between driver and device? =20
>=20
> At this point not any buffer/data... Just making sure things remain consi=
stent
> (typical case when you have multiple reads/writes to the device). That's =
why a tried
> to emphasize "accesses to the device". Maybe I should make it explicit I'=
m speaking
> about multiple reads/writes.

Talk about the data or state rather than the access to it.
Something like
'ensure consistent state obtained on multiple related accesses.'
Or if it's RMW then say that.
>=20
> - Nuno S=C3=A1
> >  =20
>=20