linux-kernel - Re: [PATCH v1 3/7] iio: adc: ina2xx: Remove unneeded dummy read to clear CNVR flag

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Message-ID: <1575331.Q2WhDFQurN@pebbles>
Date:   Sun, 10 Dec 2017 21:53:42 +0100
From:   Stefan Brüns <stefan.bruens@...h-aachen.de>
To:     Jonathan Cameron <jic23@...nel.org>
CC:     <linux-iio@...r.kernel.org>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Maciej Purski <m.purski@...sung.com>,
        <linux-kernel@...r.kernel.org>, "Andrew F . Davis" <afd@...com>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Hartmut Knaack <knaack.h@....de>,
        Javier Martinez Canillas <javier@....samsung.com>
Subject: Re: [PATCH v1 3/7] iio: adc: ina2xx: Remove unneeded dummy read to clear CNVR flag

On Sunday, December 10, 2017 6:27:33 PM CET Jonathan Cameron wrote:
> On Fri, 8 Dec 2017 18:41:48 +0100
> 
> Stefan Brüns <stefan.bruens@...h-aachen.de> wrote:
> > Although the datasheet states the CNVR flag is cleared by reading the
> > BUS_VOLTAGE register, it is actually cleared by reading any of the
> > voltage/current/power registers.
> > 
> > The behaviour has been confirmed by TI support:
> > http://e2e.ti.com/support/amplifiers/current-shunt-monitors/f/931/p/647053
> > /2378282
> > 
> > Signed-off-by: Stefan Brüns <stefan.bruens@...h-aachen.de>
> 
> I haven't checked the code thoroughly so there may well be something
> stopping it but have you checked the case where the only channel enabled is
> the timestamp?
> 
> Obviously it makes little sense, but IIRC there is nothing in the core
> preventing that happening.

The timestamp is completely unrelated to the status register, so I fail to 
understand your question. Can you please clarify?

This only removes a redundant read.

All channel combinations (w/ and w/o timestamp) work, but combinations not 
including the power register use less bus time now.

Kind regards,

Stefan

-- 
Stefan Brüns  /  Bergstraße 21  /  52062 Aachen
home: +49 241 53809034     mobile: +49 151 50412019
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