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From: Dan Robertson <dan@dlrobertson.com>
To: Jonathan Cameron <jic23@kernel.org>
Cc: linux-iio@vger.kernel.org,
	Peter Meerwald-Stadler <pmeerw@pmeerw.net>,
	devicetree@vger.kernel.org, Hartmut Knaack <knaack.h@gmx.de>,
	Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	linux-kernel@vger.kernel.org,
	Andy Shevchenko <andy.shevchenko@gmail.com>
Subject: Re: [PATCH v2 2/2] iio: (bma400) add driver for the BMA400
Date: Sat, 12 Oct 2019 16:38:39 +0000
Message-ID: <20191012163839.GB15972@nessie> (raw)
In-Reply-To: <20191012173344.7d25fd02@archlinux>

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On Sat, Oct 12, 2019 at 05:33:44PM +0100, Jonathan Cameron wrote:
> On Sat, 12 Oct 2019 15:35:56 +0000
> Dan Robertson <dan@dlrobertson.com> wrote:
> > On Sat, Oct 12, 2019 at 10:40:33AM +0100, Jonathan Cameron wrote:
> > >
> > > Silly question.  Why is soft_reset preferred to sleep mode?  
> > 
> > Not a silly question. I actually debated this when initially implementing the
> > driver. The datasheet describes soft-reset behavior in section 4.9, the
> > following snippet from the datasheet is particularly relevant:
> > 
> > > The softreset performs a fundamental reset to the device which is largely
> > > equivalent to a power cycle. Following a delay, all user configuration
> > > settings are overwritten with their default state...  
> > 
> > Sleep mode is the default power-mode, so the only real difference would be that
> > the oversampling ratio, sampling frequency, and scale would all be reset to
> > their defaults with a soft-reset. If we just set the power-mode to sleep mode,
> > the user configuration registers would be preserved.
> > 
> > I can add a comment about the behavior of a softreset in bma400_remove.
> I'd just not do it.  That way there is only the putting it to sleep path.
> We normally assume that we don't know the state during startup and aren't
> as careful on remove to make sure things are in a default state.
> 
> That way you only need a single path in the remove function. If sleep mode
> fails you are probably broken anyway.

Sounds good. That does make remove much easier if the device is not ready for a
command. I'll remove this in the next patchset version.

Cheers,

 - Dan

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  reply index

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-12  3:54 [PATCH v2 0/2] iio: add driver for Bosch BMA400 accelerometer Dan Robertson
2019-10-12  3:54 ` [PATCH v2 1/2] dt-bindings: iio: accel: bma400: add bindings Dan Robertson
2019-10-12  9:31   ` Jonathan Cameron
2019-10-12  3:54 ` [PATCH v2 2/2] iio: (bma400) add driver for the BMA400 Dan Robertson
2019-10-12  6:11   ` Randy Dunlap
2019-10-12  7:39     ` Andy Shevchenko
2019-10-12  9:29       ` Jonathan Cameron
2019-10-12  9:40   ` Jonathan Cameron
2019-10-12 15:35     ` Dan Robertson
2019-10-12 16:33       ` Jonathan Cameron
2019-10-12 16:38         ` Dan Robertson [this message]
2019-10-14 16:35   ` kbuild test robot
2019-10-15 13:53     ` Andy Shevchenko

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