Re: [PATCH v5 04/10] iio: accel: adxl345: add function to switch measuring mode

[Jonathan Cameron <jic23@kernel.org>]

On Thu,  5 Dec 2024 17:13:37 +0000
Lothar Rubusch <l.rubusch@gmail.com> wrote:

> Replace the powerup / powerdown functions by a generic function to put
> the sensor in STANDBY, or MEASURE mode. When configuring the FIFO for
> several features of the accelerometer, it is recommended to put
> measuring in STANDBY mode.
> 
> Signed-off-by: Lothar Rubusch <l.rubusch@gmail.com>
Hi Lothar,

One trivial comment inline.

Jonathan

> ---
>  drivers/iio/accel/adxl345_core.c | 44 ++++++++++++++++++++++----------
>  1 file changed, 31 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/iio/accel/adxl345_core.c b/drivers/iio/accel/adxl345_core.c
> index 98ff37271f1..1d020b0d79c 100644
> --- a/drivers/iio/accel/adxl345_core.c
> +++ b/drivers/iio/accel/adxl345_core.c
> @@ -138,6 +138,34 @@ static int adxl345_write_raw_get_fmt(struct iio_dev *indio_dev,
>  	}
>  }
>  
> +/**
> + * adxl345_set_measure_en() - Enable and disable measuring.
> + *
> + * @st: The device data.
> + * @en: Enable measurements, else standby mode.
> + *
> + * For lowest power operation, standby mode can be used. In standby mode,
> + * current consumption is supposed to be reduced to 0.1uA (typical). In this
> + * mode no measurements are made. Placing the device into standby mode
> + * preserves the contents of FIFO.
> + *
> + * Return: Returns 0 if successful, or a negative error value.
> + */
> +static int adxl345_set_measure_en(struct adxl345_state *st, bool en)
> +{
> +	unsigned int val = 0;
> +
> +	val = (en) ? ADXL345_POWER_CTL_MEASURE : ADXL345_POWER_CTL_STANDBY;
> +	return regmap_write(st->regmap, ADXL345_REG_POWER_CTL, val);
> +}
> +
> +static void adxl345_powerdown(void *ptr)
> +{
> +	struct adxl345_state *st = ptr;
> +
> +	adxl345_set_measure_en(st, false);
> +}
> +
>  static IIO_CONST_ATTR_SAMP_FREQ_AVAIL(
>  "0.09765625 0.1953125 0.390625 0.78125 1.5625 3.125 6.25 12.5 25 50 100 200 400 800 1600 3200"
>  );
> @@ -158,16 +186,6 @@ static const struct iio_info adxl345_info = {
>  	.write_raw_get_fmt	= adxl345_write_raw_get_fmt,
>  };
>  
> -static int adxl345_powerup(void *regmap)
> -{
> -	return regmap_write(regmap, ADXL345_REG_POWER_CTL, ADXL345_POWER_CTL_MEASURE);
> -}
> -
> -static void adxl345_powerdown(void *regmap)
> -{
> -	regmap_write(regmap, ADXL345_REG_POWER_CTL, ADXL345_POWER_CTL_STANDBY);
> -}
> -
>  /**
>   * adxl345_core_probe() - Probe and setup for the accelerometer.
>   * @dev:	Driver model representation of the device
> @@ -236,13 +254,13 @@ int adxl345_core_probe(struct device *dev, struct regmap *regmap,
>  				     regval, ADXL345_DEVID);
>  
>  	/* Enable measurement mode */
> -	ret = adxl345_powerup(st->regmap);
> +	ret = adxl345_set_measure_en(st, true);
>  	if (ret < 0)
>  		return dev_err_probe(dev, ret, "Failed to enable measurement mode\n");
>  
> -	ret = devm_add_action_or_reset(dev, adxl345_powerdown, st->regmap);
> +	ret = devm_add_action_or_reset(dev, adxl345_powerdown, st);
>  	if (ret < 0)
> -		return ret;
> +		return dev_err_probe(dev, ret, "Failed to add action or reset\n");
You will never see that message, though arguably that's an implementation detail.

The only error that devm_add_action_or_reset() returns is -ENOMEM;
dev_err_probe() doesn't print on -ENOMEM because enough screaming occurs at
other layers.

I normally don't bother commenting on this one if it's introduced as one of
many messages, but here you are adding just this one so I have commented.


>  
>  	return devm_iio_device_register(dev, indio_dev);
>  }