Re: [PATCH 3/7] iio: adc: ad7793: claim direct mode when writing frequency

[Daniel Baluta]

On Tue, May 24, 2016 at 10:17 PM, Alison Schofield <amsfield22@xxxxxxxxx> wrote:
> Driver was checking for direct mode and trying to lock it, but
> left a gap where mode could change before the desired operation.
> Use iio_device_claim_direct_mode() to guarantee device stays in
> direct mode.
>
> Signed-off-by: Alison Schofield <amsfield22@xxxxxxxxx>
> Cc: Daniel Baluta <daniel.baluta@xxxxxxxxx>

Acked-by: Daniel Baluta <daniel.baluta@xxxxxxxxx>

> ---
>  drivers/iio/adc/ad7793.c | 13 ++++---------
>  1 file changed, 4 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/iio/adc/ad7793.c b/drivers/iio/adc/ad7793.c
> index 7b07bb6..3f41cd8 100644
> --- a/drivers/iio/adc/ad7793.c
> +++ b/drivers/iio/adc/ad7793.c
> @@ -369,13 +369,6 @@ static ssize_t ad7793_write_frequency(struct device *dev,
>         long lval;
>         int i, ret;
>
> -       mutex_lock(&indio_dev->mlock);
> -       if (iio_buffer_enabled(indio_dev)) {
> -               mutex_unlock(&indio_dev->mlock);
> -               return -EBUSY;
> -       }
> -       mutex_unlock(&indio_dev->mlock);
> -
>         ret = kstrtol(buf, 10, &lval);
>         if (ret)
>                 return ret;
> @@ -387,12 +380,14 @@ static ssize_t ad7793_write_frequency(struct device *dev,
>
>         for (i = 0; i < 16; i++)
>                 if (lval == st->chip_info->sample_freq_avail[i]) {
> -                       mutex_lock(&indio_dev->mlock);
> +                       ret = iio_device_claim_direct_mode(indio_dev);
> +                       if (ret)
> +                               return ret;
>                         st->mode &= ~AD7793_MODE_RATE(-1);
>                         st->mode |= AD7793_MODE_RATE(i);
>                         ad_sd_write_reg(&st->sd, AD7793_REG_MODE,
>                                          sizeof(st->mode), st->mode);
> -                       mutex_unlock(&indio_dev->mlock);
> +                       iio_device_release_direct_mode(indio_dev);
>                         ret = 0;
>                 }
>
> --