Re: [PATCH 4/4] iio:pressure: preenable/postenable/predisable fixup for ST press buffer

["Ardelean, Alexandru" <alexandru.Ardelean@xxxxxxxxxx>]

On Mon, 2019-07-29 at 17:03 -0700, Denis Ciocca wrote:
> [External]
> 
> This patch is trying to cleanup for good the buffers operation functions.
> There is no need of using preenable, all can be done into
> postenable. Let's also use logical sequence of operations as
> already done in accel driver.
> Finally also rename the goto label using operation to perform and not
> where it fails.
> 

Reviewed-by: Alexandru Ardelean <alexandru.ardelean@xxxxxxxxxx>


Unrelated to this patch, I was thinking that it would be a neat idea to move the `buffer_data` allocation in
`drivers/iio/common/st_sensors/st_sensors_buffer.c`

This would remove some duplication of this alloc + free in drivers.

Maybe in st_sensors_trigger_handler() something like:

if (!sdata->buffer_data) {
    sdata->buffer_data = devm_kmalloc()
    if (!sdata->buffer_data) {
        dev_err(indio_dev->dev, "Failed to allocate buffer data\n");
        goto st_sensors_get_buffer_element_error;
    }
}

Using devm_kmalloc() or a similar devm_ variant would be neat, since it gets free'd when the device gets removed.

Thanks
Alex

> Signed-off-by: Denis Ciocca <denis.ciocca@xxxxxx>
> ---
>  drivers/iio/pressure/st_pressure_buffer.c | 32 ++++++++---------------
>  1 file changed, 11 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/iio/pressure/st_pressure_buffer.c b/drivers/iio/pressure/st_pressure_buffer.c
> index f21b630abaa0..54823cfcfab5 100644
> --- a/drivers/iio/pressure/st_pressure_buffer.c
> +++ b/drivers/iio/pressure/st_pressure_buffer.c
> @@ -29,53 +29,43 @@ int st_press_trig_set_state(struct iio_trigger *trig, bool state)
>  	return st_sensors_set_dataready_irq(indio_dev, state);
>  }
>  
> -static int st_press_buffer_preenable(struct iio_dev *indio_dev)
> -{
> -	return st_sensors_set_enable(indio_dev, true);
> -}
> -
>  static int st_press_buffer_postenable(struct iio_dev *indio_dev)
>  {
> -	int err;
>  	struct st_sensor_data *press_data = iio_priv(indio_dev);
> +	int err;
>  
>  	press_data->buffer_data = kmalloc(indio_dev->scan_bytes,
>  					  GFP_DMA | GFP_KERNEL);
> -	if (press_data->buffer_data == NULL) {
> -		err = -ENOMEM;
> -		goto allocate_memory_error;
> -	}
> +	if (!press_data->buffer_data)
> +		return -ENOMEM;
>  
>  	err = iio_triggered_buffer_postenable(indio_dev);
>  	if (err < 0)
> -		goto st_press_buffer_postenable_error;
> +		goto st_press_free_buffer;
>  
> -	return err;
> +	return st_sensors_set_enable(indio_dev, true);
>  
> -st_press_buffer_postenable_error:
> +st_press_free_buffer:
>  	kfree(press_data->buffer_data);
> -allocate_memory_error:
>  	return err;
>  }
>  
>  static int st_press_buffer_predisable(struct iio_dev *indio_dev)
>  {
> -	int err;
>  	struct st_sensor_data *press_data = iio_priv(indio_dev);
> -
> -	err = iio_triggered_buffer_predisable(indio_dev);
> -	if (err < 0)
> -		goto st_press_buffer_predisable_error;
> +	int err, err2;
>  
>  	err = st_sensors_set_enable(indio_dev, false);
>  
> -st_press_buffer_predisable_error:
> +	err2 = iio_triggered_buffer_predisable(indio_dev);
> +	if (!err)
> +		err = err2;
> +
>  	kfree(press_data->buffer_data);
>  	return err;
>  }
>  
>  static const struct iio_buffer_setup_ops st_press_buffer_setup_ops = {
> -	.preenable = &st_press_buffer_preenable,
>  	.postenable = &st_press_buffer_postenable,
>  	.predisable = &st_press_buffer_predisable,
>  };