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Date:   Sat, 20 Aug 2022 13:02:48 +0100
From:   Jonathan Cameron <jic23@kernel.org>
To:     Andy Shevchenko <andy.shevchenko@gmail.com>
Cc:     Eddie James <eajames@linux.ibm.com>,
        Lars-Peter Clausen <lars@metafoo.de>,
        linux-iio <linux-iio@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Joel Stanley <joel@jms.id.au>
Subject: Re: [PATCH v5 2/2] iio: pressure: dps310: Reset chip if MEAS_CFG is
 corrupt
Message-ID: <20220820130248.7773a6b3@jic23-huawei>
In-Reply-To: <CAHp75VegQspJJ9YT=2E3YvKh-hp9-AGincp4z0GdQbA0Vq4Zug@mail.gmail.com>
References: <20220815145705.203017-1-eajames@linux.ibm.com>
        <20220815145705.203017-3-eajames@linux.ibm.com>
        <CAHp75VegQspJJ9YT=2E3YvKh-hp9-AGincp4z0GdQbA0Vq4Zug@mail.gmail.com>
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On Thu, 18 Aug 2022 23:16:55 +0300
Andy Shevchenko <andy.shevchenko@gmail.com> wrote:

> On Mon, Aug 15, 2022 at 5:57 PM Eddie James <eajames@linux.ibm.com> wrote:
> >
> > Corruption of the MEAS_CFG register has been observed soon after
> > system boot. In order to recover this scenario, check MEAS_CFG if
> > measurement isn't ready, and if it's incorrect, reset the DPS310
> > and execute the startup procedure.  
> 
> ...
> 
> > + * Called with lock held. Returns a negative value on error, a positive value
> > + * when the device is not ready, and zero when the device is ready.  
> 
> Can we have
> 
> #define DPS310_DEVICE_NOT_READY  1
> 
> (or anonymous enum) and return it instead of abstract 1 or any other
> positive number?

Perhaps make it even clearer by returning the need to wait via another parameter
rather than this being (probably) the only place in driver with a postive rc.

bool reset_done;

rc = dps310_check_reset_meas_cfg(data, DPS310_TMP_RDY, &reset_done);

if (reset_done) {
}

> 
> ...
> 
> > +       rc = dps310_check_reset_meas_cfg(data, DPS310_TMP_RDY);
> >         if (rc < 0)
> >                 goto done;
> >
> > +       if (rc > 0) {
> > +               rate = dps310_get_temp_samp_freq(data);
> > +               timeout = DPS310_POLL_TIMEOUT_US(rate);
> > +
> > +               /*
> > +                * Poll for sensor readiness; base the timeout upon the sample
> > +                * rate.
> > +                */
> > +               rc = regmap_read_poll_timeout(data->regmap, DPS310_MEAS_CFG,
> > +                                             ready, ready & DPS310_TMP_RDY,
> > +                                             DPS310_POLL_SLEEP_US(timeout),
> > +                                             timeout);
> > +               if (rc)
> > +                       goto done;
> > +       }  
> 
> But have you tried to make a helper that takes a pointer to the
> respective function?
>