Re: [PATCH v2] iio: frequency: adf4350: Replace indio_dev->mlock with own device lock

[Jonathan Cameron <jic23@kernel.org>]

On Wed, 16 Sep 2020 12:27:31 +0300
Alexandru Ardelean <alexandru.ardelean@analog.com> wrote:

> From: Sergiu Cuciurean <sergiu.cuciurean@analog.com>
> 
> As part of the general cleanup of indio_dev->mlock, this change replaces
> it with a local lock.
> The lock protect the state of the device from potential concurrent writes.
> The device is configured via a sequence of SPI writes, and this lock is
> meant to prevent the start of another sequence before another one has
> finished.
> 
> This is part of a bigger cleanup.
> Link: https://lore.kernel.org/linux-iio/CA+U=Dsoo6YABe5ODLp+eFNPGFDjk5ZeQEceGkqjxXcVEhLWubw@mail.gmail.com/
> 
> Signed-off-by: Sergiu Cuciurean <sergiu.cuciurean@analog.com>
> Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>

Applied

> ---
>  drivers/iio/frequency/adf4350.c | 21 +++++++++++++++------
>  1 file changed, 15 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/iio/frequency/adf4350.c b/drivers/iio/frequency/adf4350.c
> index 409c9c47161e..82c050a3899d 100644
> --- a/drivers/iio/frequency/adf4350.c
> +++ b/drivers/iio/frequency/adf4350.c
> @@ -47,6 +47,13 @@ struct adf4350_state {
>  	unsigned long			regs[6];
>  	unsigned long			regs_hw[6];
>  	unsigned long long		freq_req;
> +	/*
> +	 * Lock to protect the state of the device from potential concurrent
> +	 * writes. The device is configured via a sequence of SPI writes,
> +	 * and this lock is meant to prevent the start of another sequence
> +	 * before another one has finished.
> +	 */
> +	struct mutex			lock;
>  	/*
>  	 * DMA (thus cache coherency maintenance) requires the
>  	 * transfer buffers to live in their own cache lines.
> @@ -99,7 +106,7 @@ static int adf4350_reg_access(struct iio_dev *indio_dev,
>  	if (reg > ADF4350_REG5)
>  		return -EINVAL;
>  
> -	mutex_lock(&indio_dev->mlock);
> +	mutex_lock(&st->lock);
>  	if (readval == NULL) {
>  		st->regs[reg] = writeval & ~(BIT(0) | BIT(1) | BIT(2));
>  		ret = adf4350_sync_config(st);
> @@ -107,7 +114,7 @@ static int adf4350_reg_access(struct iio_dev *indio_dev,
>  		*readval =  st->regs_hw[reg];
>  		ret = 0;
>  	}
> -	mutex_unlock(&indio_dev->mlock);
> +	mutex_unlock(&st->lock);
>  
>  	return ret;
>  }
> @@ -254,7 +261,7 @@ static ssize_t adf4350_write(struct iio_dev *indio_dev,
>  	if (ret)
>  		return ret;
>  
> -	mutex_lock(&indio_dev->mlock);
> +	mutex_lock(&st->lock);
>  	switch ((u32)private) {
>  	case ADF4350_FREQ:
>  		ret = adf4350_set_freq(st, readin);
> @@ -295,7 +302,7 @@ static ssize_t adf4350_write(struct iio_dev *indio_dev,
>  	default:
>  		ret = -EINVAL;
>  	}
> -	mutex_unlock(&indio_dev->mlock);
> +	mutex_unlock(&st->lock);
>  
>  	return ret ? ret : len;
>  }
> @@ -309,7 +316,7 @@ static ssize_t adf4350_read(struct iio_dev *indio_dev,
>  	unsigned long long val;
>  	int ret = 0;
>  
> -	mutex_lock(&indio_dev->mlock);
> +	mutex_lock(&st->lock);
>  	switch ((u32)private) {
>  	case ADF4350_FREQ:
>  		val = (u64)((st->r0_int * st->r1_mod) + st->r0_fract) *
> @@ -338,7 +345,7 @@ static ssize_t adf4350_read(struct iio_dev *indio_dev,
>  		ret = -EINVAL;
>  		val = 0;
>  	}
> -	mutex_unlock(&indio_dev->mlock);
> +	mutex_unlock(&st->lock);
>  
>  	return ret < 0 ? ret : sprintf(buf, "%llu\n", val);
>  }
> @@ -539,6 +546,8 @@ static int adf4350_probe(struct spi_device *spi)
>  	indio_dev->channels = &adf4350_chan;
>  	indio_dev->num_channels = 1;
>  
> +	mutex_init(&st->lock);
> +
>  	st->chspc = pdata->channel_spacing;
>  	if (clk) {
>  		st->clk = clk;