Re: [PATCH v4 2/3] Input: adc-joystick - Add polled input device support

[Artur Rojek <contact@artur-rojek.eu>]

On 2022-06-28 00:14, Chris Morgan wrote:
> Add polled input device support to the adc-joystick driver. This is
> useful for devices which do not have hardware capable triggers on
> their SARADC. Code modified from adc-joystick.c changes made by Maya
> Matuszczyk.
> 
> Signed-off-by: Maya Matuszczyk <maccraft123mc@gmail.com>
> Signed-off-by: Chris Morgan <macromorgan@hotmail.com>
> ---
Hey Chris,

comments inline.
>  drivers/input/joystick/adc-joystick.c | 49 +++++++++++++++++++++------
>  1 file changed, 38 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/input/joystick/adc-joystick.c
> b/drivers/input/joystick/adc-joystick.c
> index 78ebca7d400a..7e3c5083ec3c 100644
> --- a/drivers/input/joystick/adc-joystick.c
> +++ b/drivers/input/joystick/adc-joystick.c
> @@ -26,8 +26,23 @@ struct adc_joystick {
>  	struct adc_joystick_axis *axes;
>  	struct iio_channel *chans;
>  	int num_chans;
> +	bool polled;
>  };
> 
> +static void adc_joystick_poll(struct input_dev *input)
> +{
> +	struct adc_joystick *joy = input_get_drvdata(input);
> +	int i, val, ret;
> +
> +	for (i = 0; i < joy->num_chans; i++) {
> +		ret = iio_read_channel_raw(&joy->chans[i], &val);
> +		if (ret < 0)
> +			return;
> +		input_report_abs(input, joy->axes[i].code, val);
> +	}
> +	input_sync(input);
> +}
> +
>  static int adc_joystick_handle(const void *data, void *private)
>  {
>  	struct adc_joystick *joy = private;
> @@ -179,6 +194,7 @@ static int adc_joystick_probe(struct 
> platform_device *pdev)
>  	int error;
>  	int bits;
>  	int i;
> +	int value;
This name is not self-describing. How about `poll_interval` instead?
> 
>  	joy = devm_kzalloc(dev, sizeof(*joy), GFP_KERNEL);
>  	if (!joy)
> @@ -215,8 +231,15 @@ static int adc_joystick_probe(struct 
> platform_device *pdev)
>  	joy->input = input;
>  	input->name = pdev->name;
>  	input->id.bustype = BUS_HOST;
> -	input->open = adc_joystick_open;
> -	input->close = adc_joystick_close;
> +
> +	if (!device_property_read_u32(dev, "poll-interval", &value)) {
> +		joy->polled = 1;
> +		input_setup_polling(input, adc_joystick_poll);
> +		input_set_poll_interval(input, value);
> +	} else {
> +		input->open = adc_joystick_open;
> +		input->close = adc_joystick_close;
> +	}
Let's move the polling setup logic for after you establish the value of 
`joy->polled`:
```
	joy->polled = !device_property_read_u32(dev, "poll-interval",
						&poll_interval);
	if (joy->polled) {
		input_setup_polling(input, adc_joystick_poll);
		input_set_poll_interval(input, poll_interval);
	} else {
		input->open = adc_joystick_open;
		input->close = adc_joystick_close;
	}
```
This makes the intention more clear and is consistent with the `if 
(!joy->polled)` check later on.

Cheers,
Artur
> 
>  	error = adc_joystick_set_axes(dev, joy);
>  	if (error)
> @@ -229,16 +252,20 @@ static int adc_joystick_probe(struct
> platform_device *pdev)
>  		return error;
>  	}
> 
> -	joy->buffer = iio_channel_get_all_cb(dev, adc_joystick_handle, joy);
> -	if (IS_ERR(joy->buffer)) {
> -		dev_err(dev, "Unable to allocate callback buffer\n");
> -		return PTR_ERR(joy->buffer);
> -	}
> +	if (!joy->polled) {
> +		joy->buffer = iio_channel_get_all_cb(dev, adc_joystick_handle,
> +						     joy);
> +		if (IS_ERR(joy->buffer)) {
> +			dev_err(dev, "Unable to allocate callback buffer\n");
> +			return PTR_ERR(joy->buffer);
> +		}
> 
> -	error = devm_add_action_or_reset(dev, adc_joystick_cleanup, 
> joy->buffer);
> -	if (error)  {
> -		dev_err(dev, "Unable to add action\n");
> -		return error;
> +		error = devm_add_action_or_reset(dev, adc_joystick_cleanup,
> +						 joy->buffer);
> +		if (error)  {
> +			dev_err(dev, "Unable to add action\n");
> +			return error;
> +		}
>  	}
> 
>  	return 0;