Re: [PATCH v2 1/2] iio: mpl3115: add threshold events support

[Jonathan Cameron <jic23@kernel.org>]

On Fri, 31 Oct 2025 21:18:22 +0100
Antoni Pokusinski <apokusinski01@gmail.com> wrote:

> Add support for pressure and temperature rising threshold events. For
> both channels *_en and *_value (in raw units) attributes are exposed.
> 
> Since in write_event_config() the ctrl_reg1.active and ctrl_reg4
> are modified, accessing the data->ctrl_reg{1,4} in set_trigger_state()
> and write_event_config() needs to be now guarded by data->lock.
> Otherwise, it would be possible that 2 concurrent threads executing
> these functions would access the data->ctrl_reg{1,4} at the same time
> and then one would overwrite the other's result.
> 
> Signed-off-by: Antoni Pokusinski <apokusinski01@gmail.com>

Generally looks good to me, but some comments on the 24 bit value reading.

You got a lot of review quickly for this patch so I want to give some time
for follow up on v2 anyway. 

Thanks,

Jonathan


> ---
>  drivers/iio/pressure/mpl3115.c | 219 +++++++++++++++++++++++++++++++--
>  1 file changed, 209 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/iio/pressure/mpl3115.c b/drivers/iio/pressure/mpl3115.c
> index c212dfdf59ff..472e9fd65776 100644
...
> @@ -347,15 +370,45 @@ static irqreturn_t mpl3115_interrupt_handler(int irq, void *private)
>  	struct iio_dev *indio_dev = private;
>  	struct mpl3115_data *data = iio_priv(indio_dev);
>  	int ret;
> +	__be32 val_press;
> +	__be16 val_temp;
>  
>  	ret = i2c_smbus_read_byte_data(data->client, MPL3115_INT_SOURCE);
>  	if (ret < 0)
>  		return IRQ_HANDLED;
>  
> -	if (!(ret & MPL3115_INT_SRC_DRDY))
> +	if (!(ret & (MPL3115_INT_SRC_TTH | MPL3115_INT_SRC_PTH |
> +		     MPL3115_INT_SRC_DRDY)))
>  		return IRQ_NONE;
>  
> -	iio_trigger_poll_nested(data->drdy_trig);
> +	if (ret & MPL3115_INT_SRC_DRDY)
> +		iio_trigger_poll_nested(data->drdy_trig);
> +
> +	if (ret & MPL3115_INT_SRC_PTH) {
> +		iio_push_event(indio_dev,
> +			       IIO_UNMOD_EVENT_CODE(IIO_PRESSURE, 0,
> +						    IIO_EV_TYPE_THRESH,
> +						    IIO_EV_DIR_RISING),
> +						    iio_get_time_ns(indio_dev));
> +
> +		/* Reset the SRC_PTH bit in INT_SOURCE */
> +		i2c_smbus_read_i2c_block_data(data->client,
> +					      MPL3115_OUT_PRESS,
> +					      3, (u8 *)&val_press);

This is an oddity.  Why read into a __be32 when it's a 24bit number?
I guess it doesn't really matter as you just need a big enough space
and throw the value away.  However, I'd read it into a u8 [3]; then size off that
as well.

There are two existing cases of this in the driver. One of them should use
get_unaligned_be24 on a u8[3] buffer.  The other one is more complex as it's
reading directly into the scan buffer that gets pushed to the kfifo and is
reading into a u8 buffer ultimately anyway so at least there is no
real suggestion of it being 32 bits (just a +4 shift to deal with natural
alignment as the storage has to be power of 2 in that case.).

hmm. I think either we should tidy up the easy case (_read_info_raw) +
use a u8[3] here or just stick to this being odd.
My preference would be to have another patch tidying up the other case
+ use a u8[3] here.



> +	}
> +
> +	if (ret & MPL3115_INT_SRC_TTH) {
> +		iio_push_event(indio_dev,
> +			       IIO_UNMOD_EVENT_CODE(IIO_TEMP, 0,
> +						    IIO_EV_TYPE_THRESH,
> +						    IIO_EV_DIR_RISING),
> +						    iio_get_time_ns(indio_dev));
> +
> +		/* Reset the SRC_TTH bit in INT_SOURCE */
> +		i2c_smbus_read_i2c_block_data(data->client,
> +					      MPL3115_OUT_TEMP,
> +					      2, (u8 *)&val_temp);
> +	}
>  
>  	return IRQ_HANDLED;
>  }

> +
> +static int mpl3115_read_thresh(struct iio_dev *indio_dev,
> +			       const struct iio_chan_spec *chan,
> +			       enum iio_event_type type,
> +			       enum iio_event_direction dir,
> +			       enum iio_event_info info,
> +			       int *val, int *val2)
> +{
> +	struct mpl3115_data *data = iio_priv(indio_dev);
> +	int ret;
> +	__be16 tmp;
> +
> +	if (info != IIO_EV_INFO_VALUE)
> +		return -EINVAL;
> +
> +	switch (chan->type) {
> +	case IIO_PRESSURE:
> +		ret = i2c_smbus_read_i2c_block_data(data->client,
> +						    MPL3115_PRESS_TGT,
> +						    sizeof(tmp), (u8 *)&tmp);
> +		if (ret < 0)
> +			return ret;
> +
> +		/*
> +		 * Target value for the pressure is
> +		 * 16-bit unsigned value in 2 Pa units

Trivial but wrap comments to 80 char limit. Obviously doesn't really matter;
just a question of consistency.


> +		 */
> +		*val = be16_to_cpu(tmp) << 1;
> +
> +		return IIO_VAL_INT;
> +	case IIO_TEMP:
> +		ret = i2c_smbus_read_byte_data(data->client, MPL3115_TEMP_TGT);
> +		if (ret < 0)
> +			return ret;
> +
> +		/* Target value for the temperature is 8-bit 2's complement */
> +		*val = sign_extend32(ret, 7);
> +
> +		return IIO_VAL_INT;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int mpl3115_write_thresh(struct iio_dev *indio_dev,
> +				const struct iio_chan_spec *chan,
> +				enum iio_event_type type,
> +				enum iio_event_direction dir,
> +				enum iio_event_info info,
> +				int val, int val2)
> +{
> +	struct mpl3115_data *data = iio_priv(indio_dev);
> +	__be16 tmp;
> +
> +	if (info != IIO_EV_INFO_VALUE)
> +		return -EINVAL;
> +
> +	switch (chan->type) {
> +	case IIO_PRESSURE:
> +		val >>= 1;
> +
> +		if (val < 0 || val > U16_MAX)
> +			return -EINVAL;
> +
> +		tmp = cpu_to_be16(val);
> +
> +		return i2c_smbus_write_i2c_block_data(data->client,
> +						      MPL3115_PRESS_TGT,
> +						      sizeof(tmp), (u8 *)&tmp);
> +	case IIO_TEMP:
> +		if (val < S8_MIN || val > S8_MAX)
> +			return -EINVAL;
> +
> +		return i2c_smbus_write_byte_data(data->client,
> +						 MPL3115_TEMP_TGT, val);
> +	default:
> +		return -EINVAL;
> +	}
> +}