On 1/27/25 9:13 AM, Jonathan Santos wrote:
> The current locking is only preventing a triggered buffer Transfer and a
> debugfs register access from happening at the same time. If a register
> access happens during a buffered read, the action is doomed to fail anyway,
> since we need to write a magic value to exit continuous read mode.
>
> Remove locking from the trigger handler and use
> iio_device_claim_direct_mode() instead in the register access function.
>
> Signed-off-by: Jonathan Santos <Jonathan.Santos@xxxxxxxxxx>
> ---
> v2 Changes:
> * New patch in v2. It replaces the guard(mutex) patch.
> ---
> drivers/iio/adc/ad7768-1.c | 23 ++++++++++-------------
> 1 file changed, 10 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c
> index 17a49bf74637..5e2093be9b92 100644
> --- a/drivers/iio/adc/ad7768-1.c
> +++ b/drivers/iio/adc/ad7768-1.c
> @@ -271,16 +271,16 @@ static int ad7768_reg_access(struct iio_dev *indio_dev,
> struct ad7768_state *st = iio_priv(indio_dev);
> int ret;
>
> - mutex_lock(&st->lock);
> - if (readval) {
> + ret = iio_device_claim_direct_mode(indio_dev);
> + if (ret)
> + return ret;
> +
> + if (readval)
> ret = regmap_read(st->regmap, reg, readval);
> - if (ret)
> - goto err_unlock;
> - } else {
> + else
> ret = regmap_write(st->regmap, reg, writeval);
> - }
> -err_unlock:
> - mutex_unlock(&st->lock);
> +
> + iio_device_release_direct_mode(indio_dev);
>
> return ret;
> }
> @@ -495,18 +495,15 @@ static irqreturn_t ad7768_trigger_handler(int irq, void *p)
> struct ad7768_state *st = iio_priv(indio_dev);
> int ret;
>
> - mutex_lock(&st->lock);
> -
> ret = spi_read(st->spi, &st->data.scan.chan, 3);
> if (ret < 0)
> - goto err_unlock;
> + goto out;
>
> iio_push_to_buffers_with_timestamp(indio_dev, &st->data.scan,
> iio_get_time_ns(indio_dev));
>
> -err_unlock:
> +out:
> iio_trigger_notify_done(indio_dev->trig);
> - mutex_unlock(&st->lock);
>
> return IRQ_HANDLED;
> }
I think the lock can be fully removed from struct ad7768_state if it isn't
being used anymore (and remove mutex_init() in probe()).
