Re: [PATCH RFC 6/6] iio: light: opt4060: Use cleanup.h for IIO locks

[Kurt Borja]

On Thu Dec 4, 2025 at 9:42 AM -05, Nuno Sá wrote:
> On Wed, 2025-12-03 at 14:18 -0500, Kurt Borja wrote:
>> Simplify and drop "hacky" busy-waiting code in
>> opt4060_set_driver_state() by using guard().
>> 
>> Signed-off-by: Kurt Borja <kuurtb@xxxxxxxxx>
>> ---
>>  drivers/iio/light/opt4060.c | 52 +++++++++++++++------------------------------
>>  1 file changed, 17 insertions(+), 35 deletions(-)
>> 
>> diff --git a/drivers/iio/light/opt4060.c b/drivers/iio/light/opt4060.c
>> index 500899d7bd62..903963606143 100644
>> --- a/drivers/iio/light/opt4060.c
>> +++ b/drivers/iio/light/opt4060.c
>> @@ -22,6 +22,7 @@
>>  #include <linux/iio/trigger.h>
>>  #include <linux/iio/trigger_consumer.h>
>>  #include <linux/iio/triggered_buffer.h>
>> +#include <linux/cleanup.h>
>>  
>>  /* OPT4060 register set */
>>  #define OPT4060_RED_MSB				0x00
>> @@ -302,41 +303,22 @@ static int opt4060_set_driver_state(struct iio_dev *indio_dev,
>>  				    bool continuous_irq)
>>  {
>>  	struct opt4060_chip *chip = iio_priv(indio_dev);
>> -	int ret = 0;
>> -any_mode_retry:
>> -	if (!iio_device_claim_buffer(indio_dev)) {
>> -		/*
>> -		 * This one is a *bit* hacky. If we cannot claim buffer mode,
>> -		 * then try direct mode so that we make sure things cannot
>> -		 * concurrently change. And we just keep trying until we get one
>> -		 * of the modes...
>> -		 */
>> -		if (!iio_device_claim_direct(indio_dev))
>> -			goto any_mode_retry;
>> -		/*
>> -		 * This path means that we managed to claim direct mode. In
>> -		 * this case the buffer isn't enabled and it's okay to leave
>> -		 * continuous mode for sampling and/or irq.
>> -		 */
>> -		ret = opt4060_set_state_common(chip, continuous_sampling,
>> -					       continuous_irq);
>> -		iio_device_release_direct(indio_dev);
>> -		return ret;
>> -	} else {
>> -		/*
>> -		 * This path means that we managed to claim buffer mode. In
>> -		 * this case the buffer is enabled and irq and sampling must go
>> -		 * to or remain continuous, but only if the trigger is from this
>> -		 * device.
>> -		 */
>> -		if (!iio_trigger_validate_own_device(indio_dev->trig, indio_dev))
>> -			ret = opt4060_set_state_common(chip, true, true);
>> -		else
>> -			ret = opt4060_set_state_common(chip, continuous_sampling,
>> -						       continuous_irq);
>> -		iio_device_release_buffer(indio_dev);
>> -	}
>> -	return ret;
>> +
>> +	guard(iio_device_claim)(indio_dev);
>> +
>> +	/*
>> +	 * If we manage to claim buffer mode and we are using our own trigger,
>> +	 * IRQ and sampling must go to or remain continuous.
>> +	 */
>> +	if (iio_buffer_enabled(indio_dev) && iio_trigger_using_own(indio_dev))
>> +		return opt4060_set_state_common(chip, true, true);
>> +
>
> I think that if we are open coding lock(mlock) plus iio_buffer_enabled, then
> iio_device_claim kind of loses it's real meaning. To me
>
> guard(iio_device_claim)(indio_dev);
>
> it's basically iio_dev_lock

It is! That's why I think if we go down this route we should rename the
API as proposed in [1].

[1] https://lore.kernel.org/linux-iio/DEPLQT84HBAO.2GAY5BHP05HNL@xxxxxxxxx/


-- 
 ~ Kurt