Re: [PATCH 2/4] iio: adc: ad4691: add initial driver for AD4691 family

[Markus Elfring]

…
> +++ b/drivers/iio/adc/ad4691.c
> @@ -0,0 +1,1196 @@
…
> +static int ad4691_reg_access(struct iio_dev *indio_dev, unsigned int reg,
> +			     unsigned int writeval, unsigned int *readval)
> +{
…
> +	mutex_lock(&st->lock);
> +	if (readval) {
…
> +	ret = regmap_write(st->regmap, reg, writeval);
> +
> +mutex_unlock:
> +	mutex_unlock(&st->lock);
> +	return ret;
> +}
…

Under which circumstances would you become interested to apply a statement
like “guard(mutex)(&st->lock);”?
https://elixir.bootlin.com/linux/v7.0-rc1/source/include/linux/mutex.h#L253

Regards,
Markus