Re: [PATCH] iio: dac: ad5446: Replace indio_dev->mlock with own device lock

[Jonathan Cameron <jic23@kernel.org>]

On Thu, 14 May 2020 12:00:42 +0300
Sergiu Cuciurean <sergiu.cuciurean@analog.com> wrote:

> As part of the general cleanup of indio_dev->mlock, this change replaces
> it with a local lock on the device's state structure.
> 
> Signed-off-by: Sergiu Cuciurean <sergiu.cuciurean@analog.com>
Applied to the togreg branch of iio.git and pushed out as testing
for the autobuilders to play with it.

Thanks,

Jonathan

> ---
>  drivers/iio/dac/ad5446.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/iio/dac/ad5446.c b/drivers/iio/dac/ad5446.c
> index 9884e29b19b7..8f8afc8999bc 100644
> --- a/drivers/iio/dac/ad5446.c
> +++ b/drivers/iio/dac/ad5446.c
> @@ -33,6 +33,7 @@
>   * @chip_info:		chip model specific constants, available modes etc
>   * @reg:		supply regulator
>   * @vref_mv:		actual reference voltage used
> + * @lock		lock to protect the data buffer during write ops
>   */
>  
>  struct ad5446_state {
> @@ -43,6 +44,7 @@ struct ad5446_state {
>  	unsigned			cached_val;
>  	unsigned			pwr_down_mode;
>  	unsigned			pwr_down;
> +	struct mutex			lock;
>  };
>  
>  /**
> @@ -112,7 +114,7 @@ static ssize_t ad5446_write_dac_powerdown(struct iio_dev *indio_dev,
>  	if (ret)
>  		return ret;
>  
> -	mutex_lock(&indio_dev->mlock);
> +	mutex_lock(&st->lock);
>  	st->pwr_down = powerdown;
>  
>  	if (st->pwr_down) {
> @@ -123,7 +125,7 @@ static ssize_t ad5446_write_dac_powerdown(struct iio_dev *indio_dev,
>  	}
>  
>  	ret = st->chip_info->write(st, val);
> -	mutex_unlock(&indio_dev->mlock);
> +	mutex_unlock(&st->lock);
>  
>  	return ret ? ret : len;
>  }
> @@ -197,11 +199,11 @@ static int ad5446_write_raw(struct iio_dev *indio_dev,
>  			return -EINVAL;
>  
>  		val <<= chan->scan_type.shift;
> -		mutex_lock(&indio_dev->mlock);
> +		mutex_lock(&st->lock);
>  		st->cached_val = val;
>  		if (!st->pwr_down)
>  			ret = st->chip_info->write(st, val);
> -		mutex_unlock(&indio_dev->mlock);
> +		mutex_unlock(&st->lock);
>  		break;
>  	default:
>  		ret = -EINVAL;
> @@ -256,6 +258,8 @@ static int ad5446_probe(struct device *dev, const char *name,
>  	indio_dev->channels = &st->chip_info->channel;
>  	indio_dev->num_channels = 1;
>  
> +	mutex_init(&st->lock);
> +
>  	st->pwr_down_mode = MODE_PWRDWN_1k;
>  
>  	if (st->chip_info->int_vref_mv)