Re: [PATCH] iio: dac: ad5592r-base: Replace indio_dev->mlock with own device lock

["Ardelean, Alexandru" <alexandru.Ardelean@analog.com>]

On Wed, 2020-05-20 at 09:18 +0300, Sergiu Cuciurean wrote:
> [External]
> 
> As part of the general cleanup of indio_dev->mlock, this change replaces
> it with a local lock on the device's state structure.
> 

This requires a V2.
It produces a warning:

  159 |  struct iio_dev *iio_dev = iio_priv_to_dev(st);
      |                  ^~~~~~~
drivers/iio/dac/ad5592r-base.c: In function ‘ad5592r_set_channel_modes’:
drivers/iio/dac/ad5592r-base.c:200:18: warning: unused variable ‘iio_dev’
[-Wunused-variable]
  200 |  struct iio_dev *iio_dev = iio_priv_to_dev(st);


You can remove both instances of
 struct iio_dev *iio_dev = iio_priv_to_dev(st);


> Signed-off-by: Sergiu Cuciurean <sergiu.cuciurean@analog.com>
> ---
>  drivers/iio/dac/ad5592r-base.c | 28 +++++++++++++++-------------
>  drivers/iio/dac/ad5592r-base.h |  1 +
>  2 files changed, 16 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/iio/dac/ad5592r-base.c b/drivers/iio/dac/ad5592r-
> base.c
> index e2110113e884..10109eb81db2 100644
> --- a/drivers/iio/dac/ad5592r-base.c
> +++ b/drivers/iio/dac/ad5592r-base.c
> @@ -166,10 +166,10 @@ static int ad5592r_reset(struct ad5592r_state *st)
>  		udelay(1);
>  		gpiod_set_value(gpio, 1);
>  	} else {
> -		mutex_lock(&iio_dev->mlock);
> +		mutex_lock(&st->lock);
>  		/* Writing this magic value resets the device */
>  		st->ops->reg_write(st, AD5592R_REG_RESET, 0xdac);
> -		mutex_unlock(&iio_dev->mlock);
> +		mutex_unlock(&st->lock);
>  	}
>  
>  	udelay(250);
> @@ -247,7 +247,7 @@ static int ad5592r_set_channel_modes(struct
> ad5592r_state *st)
>  		}
>  	}
>  
> -	mutex_lock(&iio_dev->mlock);
> +	mutex_lock(&st->lock);
>  
>  	/* Pull down unused pins to GND */
>  	ret = ops->reg_write(st, AD5592R_REG_PULLDOWN, pulldown);
> @@ -285,7 +285,7 @@ static int ad5592r_set_channel_modes(struct
> ad5592r_state *st)
>  		ret = -EIO;
>  
>  err_unlock:
> -	mutex_unlock(&iio_dev->mlock);
> +	mutex_unlock(&st->lock);
>  	return ret;
>  }
>  
> @@ -314,11 +314,11 @@ static int ad5592r_write_raw(struct iio_dev
> *iio_dev,
>  		if (!chan->output)
>  			return -EINVAL;
>  
> -		mutex_lock(&iio_dev->mlock);
> +		mutex_lock(&st->lock);
>  		ret = st->ops->write_dac(st, chan->channel, val);
>  		if (!ret)
>  			st->cached_dac[chan->channel] = val;
> -		mutex_unlock(&iio_dev->mlock);
> +		mutex_unlock(&st->lock);
>  		return ret;
>  	case IIO_CHAN_INFO_SCALE:
>  		if (chan->type == IIO_VOLTAGE) {
> @@ -333,12 +333,12 @@ static int ad5592r_write_raw(struct iio_dev
> *iio_dev,
>  			else
>  				return -EINVAL;
>  
> -			mutex_lock(&iio_dev->mlock);
> +			mutex_lock(&st->lock);
>  
>  			ret = st->ops->reg_read(st, AD5592R_REG_CTRL,
>  						&st->cached_gp_ctrl);
>  			if (ret < 0) {
> -				mutex_unlock(&iio_dev->mlock);
> +				mutex_unlock(&st->lock);
>  				return ret;
>  			}
>  
> @@ -360,7 +360,7 @@ static int ad5592r_write_raw(struct iio_dev *iio_dev,
>  
>  			ret = st->ops->reg_write(st, AD5592R_REG_CTRL,
>  						 st->cached_gp_ctrl);
> -			mutex_unlock(&iio_dev->mlock);
> +			mutex_unlock(&st->lock);
>  
>  			return ret;
>  		}
> @@ -382,7 +382,7 @@ static int ad5592r_read_raw(struct iio_dev *iio_dev,
>  
>  	switch (m) {
>  	case IIO_CHAN_INFO_RAW:
> -		mutex_lock(&iio_dev->mlock);
> +		mutex_lock(&st->lock);
>  
>  		if (!chan->output) {
>  			ret = st->ops->read_adc(st, chan->channel,
> &read_val);
> @@ -419,7 +419,7 @@ static int ad5592r_read_raw(struct iio_dev *iio_dev,
>  		} else {
>  			int mult;
>  
> -			mutex_lock(&iio_dev->mlock);
> +			mutex_lock(&st->lock);
>  
>  			if (chan->output)
>  				mult = !!(st->cached_gp_ctrl &
> @@ -437,7 +437,7 @@ static int ad5592r_read_raw(struct iio_dev *iio_dev,
>  	case IIO_CHAN_INFO_OFFSET:
>  		ret = ad5592r_get_vref(st);
>  
> -		mutex_lock(&iio_dev->mlock);
> +		mutex_lock(&st->lock);
>  
>  		if (st->cached_gp_ctrl & AD5592R_REG_CTRL_ADC_RANGE)
>  			*val = (-34365 * 25) / ret;
> @@ -450,7 +450,7 @@ static int ad5592r_read_raw(struct iio_dev *iio_dev,
>  	}
>  
>  unlock:
> -	mutex_unlock(&iio_dev->mlock);
> +	mutex_unlock(&st->lock);
>  	return ret;
>  }
>  
> @@ -625,6 +625,8 @@ int ad5592r_probe(struct device *dev, const char
> *name,
>  	iio_dev->info = &ad5592r_info;
>  	iio_dev->modes = INDIO_DIRECT_MODE;
>  
> +	mutex_init(&st->lock);
> +
>  	ad5592r_init_scales(st, ad5592r_get_vref(st));
>  
>  	ret = ad5592r_reset(st);
> diff --git a/drivers/iio/dac/ad5592r-base.h b/drivers/iio/dac/ad5592r-
> base.h
> index 4774e4cd9c11..23dac2f1ff8a 100644
> --- a/drivers/iio/dac/ad5592r-base.h
> +++ b/drivers/iio/dac/ad5592r-base.h
> @@ -52,6 +52,7 @@ struct ad5592r_state {
>  	struct regulator *reg;
>  	struct gpio_chip gpiochip;
>  	struct mutex gpio_lock;	/* Protect cached gpio_out, gpio_val,
> etc. */
> +	struct mutex lock;
>  	unsigned int num_channels;
>  	const struct ad5592r_rw_ops *ops;
>  	int scale_avail[2][2];