linux-kernel - Re: [PATCH] iio: magnetometer: mag3110: claim direct mode during raw reads

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Date:	Mon, 15 Aug 2016 17:04:24 +0100
From:	Jonathan Cameron <jic23@...nel.org>
To:	Alison Schofield <amsfield22@...il.com>
Cc:	knaack.h@....de, lars@...afoo.de, pmeerw@...erw.net,
	linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] iio: magnetometer: mag3110: claim direct mode during raw
 reads

On 01/08/16 16:48, Alison Schofield wrote:
> Driver was checking for direct mode but not locking it.  Use
> claim/release helper functions to guarantee the device stays
> in direct mode during raw reads.
> 
> Signed-off-by: Alison Schofield <amsfield22@...il.com>
> Cc: Daniel Baluta <daniel.baluta@...il.com>
> ---
>  drivers/iio/magnetometer/mag3110.c | 21 +++++++++++++--------
>  1 file changed, 13 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/iio/magnetometer/mag3110.c b/drivers/iio/magnetometer/mag3110.c
> index f2be4a0..90574ff 100644
> --- a/drivers/iio/magnetometer/mag3110.c
> +++ b/drivers/iio/magnetometer/mag3110.c
> @@ -154,34 +154,39 @@ static int mag3110_read_raw(struct iio_dev *indio_dev,
>  
>  	switch (mask) {
>  	case IIO_CHAN_INFO_RAW:
> -		if (iio_buffer_enabled(indio_dev))
> -			return -EBUSY;
> +		ret = iio_device_claim_direct_mode(indio_dev);
> +		if (ret)
> +			return ret;
>  
>  		switch (chan->type) {
>  		case IIO_MAGN: /* in 0.1 uT / LSB */
>  			ret = mag3110_read(data, buffer);
>  			if (ret < 0)
> -				return ret;
> +				goto release;
>  			*val = sign_extend32(
>  				be16_to_cpu(buffer[chan->scan_index]), 15);
> -			return IIO_VAL_INT;
> +			ret = IIO_VAL_INT;
No break?
>  		case IIO_TEMP: /* in 1 C / LSB */
>  			mutex_lock(&data->lock);
>  			ret = mag3110_request(data);
>  			if (ret < 0) {
>  				mutex_unlock(&data->lock);
> -				return ret;
> +				goto release;
>  			}
>  			ret = i2c_smbus_read_byte_data(data->client,
>  				MAG3110_DIE_TEMP);
>  			mutex_unlock(&data->lock);
>  			if (ret < 0)
> -				return ret;
> +				goto release;
>  			*val = sign_extend32(ret, 7);
> -			return IIO_VAL_INT;
> +			ret = IIO_VAL_INT;
No break here either....
>  		default:
> -			return -EINVAL;
> +			ret = -EINVAL;
>  		}
> +release:
> +		iio_device_release_direct_mode(indio_dev);
> +		return ret;
> +
>  	case IIO_CHAN_INFO_SCALE:
>  		switch (chan->type) {
>  		case IIO_MAGN:
>