Re: [PATCH v3] staging: ad7606: Replace mlock with driver private lock

[Jonathan Cameron <jic23@kernel.org>]

On 20/03/17 19:51, Arushi Singhal wrote:
> The IIO subsystem is redefining iio_dev->mlock to be used by
> the IIO core only for protecting device operating mode changes.
> ie. Changes between INDIO_DIRECT_MODE, INDIO_BUFFER_* modes.
> 
> In this driver, mlock was being used to protect hardware state
> changes.  Replace it with a lock in the devices global data.
> 
> Signed-off-by: Arushi Singhal <arushisinghal19971997@gmail.com>
Nice patch.

Applied to the togreg branch of iio.git and pushed out as testing for
the autobuilders to play with it.

Thanks,

Jonathan
> ---
>  changes in v3
>  - Add mutex_init.
>  - correct the Documentation.
> 
>  drivers/staging/iio/adc/ad7606.c | 9 +++++----
>  drivers/staging/iio/adc/ad7606.h | 3 +++
>  2 files changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/staging/iio/adc/ad7606.c b/drivers/staging/iio/adc/ad7606.c
> index 9dbfa64b1e53..18f5f139117e 100644
> --- a/drivers/staging/iio/adc/ad7606.c
> +++ b/drivers/staging/iio/adc/ad7606.c
> @@ -208,7 +208,7 @@ static int ad7606_write_raw(struct iio_dev *indio_dev,
>  	switch (mask) {
>  	case IIO_CHAN_INFO_SCALE:
>  		ret = -EINVAL;
> -		mutex_lock(&indio_dev->mlock);
> +		mutex_lock(&st->lock);
>  		for (i = 0; i < ARRAY_SIZE(scale_avail); i++)
>  			if (val2 == scale_avail[i][1]) {
>  				gpiod_set_value(st->gpio_range, i);
> @@ -217,7 +217,7 @@ static int ad7606_write_raw(struct iio_dev *indio_dev,
>  				ret = 0;
>  				break;
>  			}
> -		mutex_unlock(&indio_dev->mlock);
> +		mutex_unlock(&st->lock);
>  
>  		return ret;
>  	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
> @@ -231,11 +231,11 @@ static int ad7606_write_raw(struct iio_dev *indio_dev,
>  		values[1] = (ret >> 1) & 1;
>  		values[2] = (ret >> 2) & 1;
>  
> -		mutex_lock(&indio_dev->mlock);
> +		mutex_lock(&st->lock);
>  		gpiod_set_array_value(ARRAY_SIZE(values), st->gpio_os->desc,
>  				      values);
>  		st->oversampling = val;
> -		mutex_unlock(&indio_dev->mlock);
> +		mutex_unlock(&st->lock);
>  
>  		return 0;
>  	default:
> @@ -413,6 +413,7 @@ int ad7606_probe(struct device *dev, int irq, void __iomem *base_address,
>  	st = iio_priv(indio_dev);
>  
>  	st->dev = dev;
> +	mutex_init(&st->lock);
>  	st->bops = bops;
>  	st->base_address = base_address;
>  	/* tied to logic low, analog input range is +/- 5V */
> diff --git a/drivers/staging/iio/adc/ad7606.h b/drivers/staging/iio/adc/ad7606.h
> index 746f9553d2ba..acaed8d5379c 100644
> --- a/drivers/staging/iio/adc/ad7606.h
> +++ b/drivers/staging/iio/adc/ad7606.h
> @@ -14,6 +14,7 @@
>   * @name:		identification string for chip
>   * @channels:		channel specification
>   * @num_channels:	number of channels
> + * @lock		protect sensor state
>   */
>  
>  struct ad7606_chip_info {
> @@ -23,6 +24,7 @@ struct ad7606_chip_info {
>  
>  /**
>   * struct ad7606_state - driver instance specific data
> + * @lock		protect sensor state
>   */
>  
>  struct ad7606_state {
> @@ -37,6 +39,7 @@ struct ad7606_state {
>  	bool				done;
>  	void __iomem			*base_address;
>  
> +	struct mutex			lock; /* protect sensor state */
>  	struct gpio_desc		*gpio_convst;
>  	struct gpio_desc		*gpio_reset;
>  	struct gpio_desc		*gpio_range;
>