linux-kernel - Re: [PATCH] iio: dac: ad5421: Replace indio

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Date:   Sat, 16 May 2020 16:27:34 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     Sergiu Cuciurean <sergiu.cuciurean@...log.com>
Cc:     <linux-kernel@...r.kernel.org>, <linux-iio@...r.kernel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Michael Hennerich <Michael.Hennerich@...log.com>,
        Stefan Popa <stefan.popa@...log.com>,
        Hartmut Knaack <knaack.h@....de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>
Subject: Re: [PATCH] iio: dac: ad5421: Replace indio_dev->mlock with own
 device lock

On Thu, 14 May 2020 12:17:53 +0300
Sergiu Cuciurean <sergiu.cuciurean@...log.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@...log.com>
Applied.

Thanks,

J

> ---
>  drivers/iio/dac/ad5421.c | 21 +++++++++++++--------
>  1 file changed, 13 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/iio/dac/ad5421.c b/drivers/iio/dac/ad5421.c
> index 63063e85cd0a..fec27764cea8 100644
> --- a/drivers/iio/dac/ad5421.c
> +++ b/drivers/iio/dac/ad5421.c
> @@ -62,12 +62,14 @@
>   * @current_range:	current range which the device is configured for
>   * @data:		spi transfer buffers
>   * @fault_mask:		software masking of events
> + * @lock	lock to protect the data buffer during SPI ops
>   */
>  struct ad5421_state {
>  	struct spi_device		*spi;
>  	unsigned int			ctrl;
>  	enum ad5421_current_range	current_range;
>  	unsigned int			fault_mask;
> +	struct mutex			lock;
>  
>  	/*
>  	 * DMA (thus cache coherency maintenance) requires the
> @@ -142,11 +144,12 @@ static int ad5421_write_unlocked(struct iio_dev *indio_dev,
>  static int ad5421_write(struct iio_dev *indio_dev, unsigned int reg,
>  	unsigned int val)
>  {
> +	struct ad5421_state *st = iio_priv(indio_dev);
>  	int ret;
>  
> -	mutex_lock(&indio_dev->mlock);
> +	mutex_lock(&st->lock);
>  	ret = ad5421_write_unlocked(indio_dev, reg, val);
> -	mutex_unlock(&indio_dev->mlock);
> +	mutex_unlock(&st->lock);
>  
>  	return ret;
>  }
> @@ -166,7 +169,7 @@ static int ad5421_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));
>  
> @@ -174,7 +177,7 @@ static int ad5421_read(struct iio_dev *indio_dev, unsigned int reg)
>  	if (ret >= 0)
>  		ret = be32_to_cpu(st->data[1].d32) & 0xffff;
>  
> -	mutex_unlock(&indio_dev->mlock);
> +	mutex_unlock(&st->lock);
>  
>  	return ret;
>  }
> @@ -185,14 +188,14 @@ static int ad5421_update_ctrl(struct iio_dev *indio_dev, unsigned int set,
>  	struct ad5421_state *st = iio_priv(indio_dev);
>  	unsigned int ret;
>  
> -	mutex_lock(&indio_dev->mlock);
> +	mutex_lock(&st->lock);
>  
>  	st->ctrl &= ~clr;
>  	st->ctrl |= set;
>  
>  	ret = ad5421_write_unlocked(indio_dev, AD5421_REG_CTRL, st->ctrl);
>  
> -	mutex_unlock(&indio_dev->mlock);
> +	mutex_unlock(&st->lock);
>  
>  	return ret;
>  }
> @@ -400,12 +403,12 @@ static int ad5421_write_event_config(struct iio_dev *indio_dev,
>  		return -EINVAL;
>  	}
>  
> -	mutex_lock(&indio_dev->mlock);
> +	mutex_lock(&st->lock);
>  	if (state)
>  		st->fault_mask |= mask;
>  	else
>  		st->fault_mask &= ~mask;
> -	mutex_unlock(&indio_dev->mlock);
> +	mutex_unlock(&st->lock);
>  
>  	return 0;
>  }
> @@ -491,6 +494,8 @@ static int ad5421_probe(struct spi_device *spi)
>  	indio_dev->channels = ad5421_channels;
>  	indio_dev->num_channels = ARRAY_SIZE(ad5421_channels);
>  
> +	mutex_init(&st->lock);
> +
>  	st->ctrl = AD5421_CTRL_WATCHDOG_DISABLE |
>  			AD5421_CTRL_AUTO_FAULT_READBACK;
>