linux-kernel - Re: [PATCH] iio: pressure: ms5611: claim direct mode during oversampling changes

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Date:   Sat, 21 Jan 2017 12:32:14 +0000
From:   Jonathan Cameron <jic23@...nel.org>
To:     Alison Schofield <amsfield22@...il.com>
Cc:     tduszyns@...il.com, knaack.h@....de, lars@...afoo.de,
        pmeerw@...erw.net, linux-iio@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] iio: pressure: ms5611: claim direct mode during
 oversampling changes

On 20/01/17 20:22, Alison Schofield wrote:
> Driver was checking for direct mode before changing oversampling
> ratios, but was not locking it.  Use the claim/release helper
> functions to guarantee the device stays in direct mode while the
> oversampling ratios are being updated.  Continue to use the drivers
> private state lock to protect against conflicting direct mode access
> of the state data.
> 
> Signed-off-by: Alison Schofield <amsfield22@...il.com>
I think this one is straight forward enough that I'm happy to take it
without confirmation from Thomaz.  

Anyone feel free to shout if I am missing something.

Thanks,

Jonathan
> ---
>  drivers/iio/pressure/ms5611_core.c | 12 +++++++-----
>  1 file changed, 7 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/iio/pressure/ms5611_core.c b/drivers/iio/pressure/ms5611_core.c
> index 6bd53e7..2a77a2f 100644
> --- a/drivers/iio/pressure/ms5611_core.c
> +++ b/drivers/iio/pressure/ms5611_core.c
> @@ -308,6 +308,7 @@ static int ms5611_write_raw(struct iio_dev *indio_dev,
>  {
>  	struct ms5611_state *st = iio_priv(indio_dev);
>  	const struct ms5611_osr *osr = NULL;
> +	int ret;
>  
>  	if (mask != IIO_CHAN_INFO_OVERSAMPLING_RATIO)
>  		return -EINVAL;
> @@ -321,12 +322,11 @@ static int ms5611_write_raw(struct iio_dev *indio_dev,
>  	if (!osr)
>  		return -EINVAL;
>  
> -	mutex_lock(&st->lock);
> +	ret = iio_device_claim_direct_mode(indio_dev);
> +	if (ret)
> +		return ret;
>  
> -	if (iio_buffer_enabled(indio_dev)) {
> -		mutex_unlock(&st->lock);
> -		return -EBUSY;
> -	}
> +	mutex_lock(&st->lock);
>  
>  	if (chan->type == IIO_TEMP)
>  		st->temp_osr = osr;
> @@ -334,6 +334,8 @@ static int ms5611_write_raw(struct iio_dev *indio_dev,
>  		st->pressure_osr = osr;
>  
>  	mutex_unlock(&st->lock);
> +	iio_device_release_direct_mode(indio_dev);
> +
>  	return 0;
>  }
>  
>