linux-kernel - Re: [PATCH v2] iio: light: ltr501: claim direct mode during select raw reads

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Message-ID: <bb21bb38-4121-3652-7047-df1aed9a5387@kernel.org>
Date:   Sun, 16 Oct 2016 14:24:40 +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 v2] iio: light: ltr501: claim direct mode during select
 raw reads

On 16/10/16 06:00, 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 required raw read cases.
> 
> Signed-off-by: Alison Schofield <amsfield22@...il.com>
Very nice.

Applied to the togreg branch fo iio.git and pushed out as testing.
Peter, if you have any comments on this, there is still plenty of
time as I won't send a pull request until at lest next weekend.

Jonathan
> ---
> Changes in v2:
>  Reworked IIO_CHAN_INFO_RAW case so claim and release are
>  executed at same level in the switch statements. (rather
>  than claims on top level and releases nested in cases)
> 
>  drivers/iio/light/ltr501.c | 30 ++++++++++++++++++++----------
>  1 file changed, 20 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/iio/light/ltr501.c b/drivers/iio/light/ltr501.c
> index 3afc53a..d577477 100644
> --- a/drivers/iio/light/ltr501.c
> +++ b/drivers/iio/light/ltr501.c
> @@ -631,14 +631,16 @@ static int ltr501_read_raw(struct iio_dev *indio_dev,
>  
>  	switch (mask) {
>  	case IIO_CHAN_INFO_PROCESSED:
> -		if (iio_buffer_enabled(indio_dev))
> -			return -EBUSY;
> -
>  		switch (chan->type) {
>  		case IIO_LIGHT:
> +			ret = iio_device_claim_direct_mode(indio_dev);
> +			if (ret)
> +				return ret;
> +
>  			mutex_lock(&data->lock_als);
>  			ret = ltr501_read_als(data, buf);
>  			mutex_unlock(&data->lock_als);
> +			iio_device_release_direct_mode(indio_dev);
>  			if (ret < 0)
>  				return ret;
>  			*val = ltr501_calculate_lux(le16_to_cpu(buf[1]),
> @@ -648,8 +650,9 @@ static int ltr501_read_raw(struct iio_dev *indio_dev,
>  			return -EINVAL;
>  		}
>  	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_INTENSITY:
> @@ -657,21 +660,28 @@ static int ltr501_read_raw(struct iio_dev *indio_dev,
>  			ret = ltr501_read_als(data, buf);
>  			mutex_unlock(&data->lock_als);
>  			if (ret < 0)
> -				return ret;
> +				break;
>  			*val = le16_to_cpu(chan->address == LTR501_ALS_DATA1 ?
>  					   buf[0] : buf[1]);
> -			return IIO_VAL_INT;
> +			ret = IIO_VAL_INT;
> +			break;
>  		case IIO_PROXIMITY:
>  			mutex_lock(&data->lock_ps);
>  			ret = ltr501_read_ps(data);
>  			mutex_unlock(&data->lock_ps);
>  			if (ret < 0)
> -				return ret;
> +				break;
>  			*val = ret & LTR501_PS_DATA_MASK;
> -			return IIO_VAL_INT;
> +			ret = IIO_VAL_INT;
> +			break;
>  		default:
> -			return -EINVAL;
> +			ret = -EINVAL;
> +			break;
>  		}
> +
> +		iio_device_release_direct_mode(indio_dev);
> +		return ret;
> +
>  	case IIO_CHAN_INFO_SCALE:
>  		switch (chan->type) {
>  		case IIO_INTENSITY:
>