linux-kernel - Re: [PATCH v2 06/22] iio: accel: adxl345: add function to switch measuring

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Message-ID: <20241124181007.24fce875@jic23-huawei>
Date: Sun, 24 Nov 2024 18:10:07 +0000
From: Jonathan Cameron <jic23@...nel.org>
To: Lothar Rubusch <l.rubusch@...il.com>
Cc: lars@...afoo.de, Michael.Hennerich@...log.com,
 linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
 eraretuya@...il.com
Subject: Re: [PATCH v2 06/22] iio: accel: adxl345: add function to switch
 measuring

On Sun, 17 Nov 2024 18:26:35 +0000
Lothar Rubusch <l.rubusch@...il.com> wrote:

> Replace the powerup / powerdown functions by a generic function to put
> the sensor in STANDBY, or MEASURE mode. This is needed for several
> features of the accelerometer. It allows to change e.g. FIFO settings.
> 
> Signed-off-by: Lothar Rubusch <l.rubusch@...il.com>
> ---
>  drivers/iio/accel/adxl345_core.c | 53 ++++++++++++++++++++++----------
>  1 file changed, 37 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/iio/accel/adxl345_core.c b/drivers/iio/accel/adxl345_core.c
> index 926e397678..81688a9eaf 100644
> --- a/drivers/iio/accel/adxl345_core.c
> +++ b/drivers/iio/accel/adxl345_core.c
> @@ -138,6 +138,39 @@ 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 adxl34x_state *st, bool en)
> +{
> +	unsigned int val = 0;
> +	int ret;
> +
> +	val = (en) ? ADXL345_POWER_CTL_MEASURE : ADXL345_POWER_CTL_STANDBY;
> +	ret = regmap_write(st->regmap, ADXL345_REG_POWER_CTL, val);
> +	if (ret)
> +		return -EINVAL;
Don't eat the error response from regmap_write. I will probably be more
useful than simple -EINVAL if we get a problem.

	return regmap_write()

> +
> +	return 0;
> +}
> +
> +static void adxl345_powerdown(void *ptr)
> +{
> +	struct adxl34x_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 +191,6 @@ 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 adxl345 accelerometer,
>   *                        also covers the adxl375 and adxl346 accelerometer
> @@ -242,14 +265,12 @@ int adxl345_core_probe(struct device *dev, struct regmap *regmap,
>  		return dev_err_probe(dev, -ENODEV, "Invalid device ID: %x, expected %x\n",
>  				     regval, ADXL345_DEVID);
>  
> -	/* Enable measurement mode */
> -	ret = adxl345_powerup(st->regmap);
> +	ret = devm_add_action_or_reset(dev, adxl345_powerdown, st);

This should be done after the call to turn the device on.  Otherwise we are powering
down a device that is already powered down if this returns an error.
So original ordering looks correct to me.


>  	if (ret < 0)
> -		return dev_err_probe(dev, ret, "Failed to enable measurement mode\n");
> +		return dev_err_probe(dev, ret, "Failed to add action or reset\n");
>  
> -	ret = devm_add_action_or_reset(dev, adxl345_powerdown, st->regmap);
> -	if (ret < 0)
> -		return ret;
> +	/* Enable measurement mode */
> +	adxl345_set_measure_en(st, true);
Check if this fails.

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