| Message ID | 20210902211437.503623-12-miquel.raynal@bootlin.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | Bring external triggers support to MAX1027-like ADCs | expand |
On Thu, 2 Sep 2021 23:14:32 +0200 Miquel Raynal <miquel.raynal@bootlin.com> wrote: > When hardware buffers are enabled (the cnvst pin being the trigger), one > should not mess with the device state by requesting a single channel > read. > > There is already a iio_buffer_enabled() check in *_read_single_value() > to merely prevent this situation but the check is inconsistent since > buffers can be enabled after the if clause anyway. Instead, use the core > mutex by calling iio_device_claim/release_direct_mode(). > > Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com> > --- > drivers/iio/adc/max1027.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/drivers/iio/adc/max1027.c b/drivers/iio/adc/max1027.c > index f4cb5c75604b..57f62ea2d7aa 100644 > --- a/drivers/iio/adc/max1027.c > +++ b/drivers/iio/adc/max1027.c > @@ -296,10 +296,9 @@ static int max1027_read_single_value(struct iio_dev *indio_dev, > int ret; > struct max1027_state *st = iio_priv(indio_dev); > > - if (iio_buffer_enabled(indio_dev)) { > - dev_warn(&indio_dev->dev, "trigger mode already enabled"); > - return -EBUSY; > - } > + ret = iio_device_claim_direct_mode(indio_dev); > + if (ret) > + return ret; > > /* Configure conversion register with the requested chan */ > st->reg = MAX1027_CONV_REG | MAX1027_CHAN(chan->channel) | > @@ -325,6 +324,8 @@ static int max1027_read_single_value(struct iio_dev *indio_dev, > if (ret < 0) > return ret; Must also be released in error paths. Treat it like a lock (there is one internally) so to avoid permanent deadlock we must release it even if things are going wrong > > + iio_device_release_direct_mode(indio_dev); > + > *val = be16_to_cpu(st->buffer[0]); > > return IIO_VAL_INT;
diff --git a/drivers/iio/adc/max1027.c b/drivers/iio/adc/max1027.c index f4cb5c75604b..57f62ea2d7aa 100644 --- a/drivers/iio/adc/max1027.c +++ b/drivers/iio/adc/max1027.c @@ -296,10 +296,9 @@ static int max1027_read_single_value(struct iio_dev *indio_dev, int ret; struct max1027_state *st = iio_priv(indio_dev); - if (iio_buffer_enabled(indio_dev)) { - dev_warn(&indio_dev->dev, "trigger mode already enabled"); - return -EBUSY; - } + ret = iio_device_claim_direct_mode(indio_dev); + if (ret) + return ret; /* Configure conversion register with the requested chan */ st->reg = MAX1027_CONV_REG | MAX1027_CHAN(chan->channel) | @@ -325,6 +324,8 @@ static int max1027_read_single_value(struct iio_dev *indio_dev, if (ret < 0) return ret; + iio_device_release_direct_mode(indio_dev); + *val = be16_to_cpu(st->buffer[0]); return IIO_VAL_INT;
When hardware buffers are enabled (the cnvst pin being the trigger), one should not mess with the device state by requesting a single channel read. There is already a iio_buffer_enabled() check in *_read_single_value() to merely prevent this situation but the check is inconsistent since buffers can be enabled after the if clause anyway. Instead, use the core mutex by calling iio_device_claim/release_direct_mode(). Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com> --- drivers/iio/adc/max1027.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-)