Re: [PATCH v12 2/3] Input: adc-joystick - Add polled input device support

[Jonathan Cameron <jic23@kernel.org>]

On Fri,  5 Aug 2022 12:10:15 -0500
Chris Morgan <macroalpha82@gmail.com> wrote:

> From: Chris Morgan <macromorgan@hotmail.com>
> 
> 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>
Hi Chris,

Trying to avoid too much indentation has lead to an odd code structure.
Still minor thing, so either way this looks fine to me.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

> ---
>  drivers/input/joystick/adc-joystick.c | 44 +++++++++++++++++++++++++--
>  1 file changed, 41 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/input/joystick/adc-joystick.c b/drivers/input/joystick/adc-joystick.c
> index 78ebca7d400a..77dfb7dd96eb 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;
> +	unsigned int poll_interval;
>  
>  	joy = devm_kzalloc(dev, sizeof(*joy), GFP_KERNEL);
>  	if (!joy)
> @@ -192,8 +208,21 @@ static int adc_joystick_probe(struct platform_device *pdev)
>  		return error;
>  	}
>  
> -	/* Count how many channels we got. NULL terminated. */
> +	if (device_property_present(dev, "poll-interval")) {
> +		error = device_property_read_u32(dev, "poll-interval",
> +						 &poll_interval);
> +		if (error)
> +			return error;
> +		joy->polled = true;
> +	}
> +
> +	/*
> +	 * Count how many channels we got. NULL terminated.
> +	 * Do not check the storage size if using polling.
> +	 */
>  	for (i = 0; joy->chans[i].indio_dev; i++) {
> +		if (joy->polled)
> +			continue;

Whilst I can see why did this, it is a rather 'unusual' code structure
and that makes me a tiny bit uncomfortable. However if everyone else
is happy with this then fair enough (I see it was Artur's suggestion to
handle it like this).

>  		bits = joy->chans[i].channel->scan_type.storagebits;
>  		if (!bits || bits > 16) {
>  			dev_err(dev, "Unsupported channel storage size\n");
> @@ -215,8 +244,14 @@ 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 (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;
> +	}
>  
>  	error = adc_joystick_set_axes(dev, joy);
>  	if (error)
> @@ -229,6 +264,9 @@ static int adc_joystick_probe(struct platform_device *pdev)
>  		return error;
>  	}
>  
> +	if (joy->polled)
> +		return 0;
> +
>  	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");