linux-kernel - Re: [PATCH v8 2/2] iio: pressure: dps310: Reset chip after timeout

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Message-ID: <CAHp75VfEktq10YcQMF9D9cQWtVsR+gx+3_PAq1YNoKUWEZaC1Q@mail.gmail.com>
Date:   Fri, 16 Sep 2022 08:51:13 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Eddie James <eajames@...ux.ibm.com>
Cc:     jic23@...nel.org, lars@...afoo.de, linux-iio@...r.kernel.org,
        joel@....id.au, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org
Subject: Re: [PATCH v8 2/2] iio: pressure: dps310: Reset chip after timeout

On Thu, Sep 15, 2022 at 10:57 PM Eddie James <eajames@...ux.ibm.com> wrote:
>
> The DPS310 chip has been observed to get "stuck" such that pressure
> and temperature measurements are never indicated as "ready" in the
> MEAS_CFG register. The only solution is to reset the device and try
> again. In order to avoid continual failures, use a boolean flag to
> only try the reset after timeout once if errors persist.

...

> +static int dps310_ready(struct dps310_data *data, int ready_bit, int timeout)
> +{
> +       int rc;
> +
> +       rc = dps310_ready_status(data, ready_bit, timeout);
> +       if (rc) {

> +               if (rc == -ETIMEDOUT && !data->timeout_recovery_failed) {

Here you compare rc with a certain error code...

> +                       /* Reset and reinitialize the chip. */
> +                       if (dps310_reset_reinit(data)) {
> +                               data->timeout_recovery_failed = true;
> +                       } else {
> +                               /* Try again to get sensor ready status. */

> +                               if (dps310_ready_status(data, ready_bit, timeout))

...but here you assume that the only error code is -ETIMEDOUT. It's
kinda inconsistent (if you rely on internals of ready_status, then why
to check the certain error code, or otherwise why not to return a real
second error code). That's why I asked about re-using rc here.

In any case I don't think this justifies a v9, let's wait for your
answer and Jonathan's opinion.

> +                                       data->timeout_recovery_failed = true;
> +                               else
> +                                       return 0;
> +                       }
> +               }
> +
> +               return rc;
> +       }
> +
> +       data->timeout_recovery_failed = false;
> +       return 0;
> +}

-- 
With Best Regards,
Andy Shevchenko