Re: [PATCH] iio: dac: ad5764: Replace indio_dev->mlock with own device lock

[Jonathan Cameron <jic23@kernel.org>]

On Thu, 14 May 2020 12:12:12 +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.

Thanks,

Jonathan

> ---
>  drivers/iio/dac/ad5764.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/iio/dac/ad5764.c b/drivers/iio/dac/ad5764.c
> index f7ab211604a1..5b0f0fe354f6 100644
> --- a/drivers/iio/dac/ad5764.c
> +++ b/drivers/iio/dac/ad5764.c
> @@ -46,6 +46,7 @@ struct ad5764_chip_info {
>   * @spi:		spi_device
>   * @chip_info:		chip info
>   * @vref_reg:		vref supply regulators
> + * @lock		lock to protect the data buffer during SPI ops
>   * @data:		spi transfer buffers
>   */
>  
> @@ -53,6 +54,7 @@ struct ad5764_state {
>  	struct spi_device		*spi;
>  	const struct ad5764_chip_info	*chip_info;
>  	struct regulator_bulk_data	vref_reg[2];
> +	struct mutex			lock;
>  
>  	/*
>  	 * DMA (thus cache coherency maintenance) requires the
> @@ -126,11 +128,11 @@ static int ad5764_write(struct iio_dev *indio_dev, unsigned int reg,
>  	struct ad5764_state *st = iio_priv(indio_dev);
>  	int ret;
>  
> -	mutex_lock(&indio_dev->mlock);
> +	mutex_lock(&st->lock);
>  	st->data[0].d32 = cpu_to_be32((reg << 16) | val);
>  
>  	ret = spi_write(st->spi, &st->data[0].d8[1], 3);
> -	mutex_unlock(&indio_dev->mlock);
> +	mutex_unlock(&st->lock);
>  
>  	return ret;
>  }
> @@ -151,7 +153,7 @@ static int ad5764_read(struct iio_dev *indio_dev, unsigned int reg,
>  		},
>  	};
>  
> -	mutex_lock(&indio_dev->mlock);
> +	mutex_lock(&st->lock);
>  
>  	st->data[0].d32 = cpu_to_be32((1 << 23) | (reg << 16));
>  
> @@ -159,7 +161,7 @@ static int ad5764_read(struct iio_dev *indio_dev, unsigned int reg,
>  	if (ret >= 0)
>  		*val = be32_to_cpu(st->data[1].d32) & 0xffff;
>  
> -	mutex_unlock(&indio_dev->mlock);
> +	mutex_unlock(&st->lock);
>  
>  	return ret;
>  }
> @@ -295,6 +297,8 @@ static int ad5764_probe(struct spi_device *spi)
>  	indio_dev->num_channels = AD5764_NUM_CHANNELS;
>  	indio_dev->channels = st->chip_info->channels;
>  
> +	mutex_init(&st->lock);
> +
>  	if (st->chip_info->int_vref == 0) {
>  		st->vref_reg[0].supply = "vrefAB";
>  		st->vref_reg[1].supply = "vrefCD";