linux-kernel - Re: [PATCH v5 2/2] iio: pressure: dps310: Reset chip if MEAS

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Date:   Tue, 6 Sep 2022 14:41:30 -0500
From:   Eddie James <eajames@...ux.ibm.com>
To:     Jonathan Cameron <jic23@...nel.org>,
        Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Lars-Peter Clausen <lars@...afoo.de>,
        linux-iio <linux-iio@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Joel Stanley <joel@....id.au>
Subject: Re: [PATCH v5 2/2] iio: pressure: dps310: Reset chip if MEAS_CFG is
 corrupt


On 8/20/22 07:02, Jonathan Cameron wrote:
> On Thu, 18 Aug 2022 23:16:55 +0300
> Andy Shevchenko <andy.shevchenko@...il.com> wrote:
>
>> On Mon, Aug 15, 2022 at 5:57 PM Eddie James <eajames@...ux.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) {
> }


Thanks for the feedback.

Unfortunately our issue is still presenting itself even with a correct 
MEAS_CFG register. The sensor ready bit never gets set. So I'm going to 
rework this patch to reset the device after a timeout.


Thanks,

Eddie


>
>> ...
>>
>>> +       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?
>>