Re: [PATCH v2 2/3] Input: adc-joystick - Add polled input device support

["Heiko Stübner" <heiko@sntech.de>]

Am Mittwoch, 1. Juni 2022, 22:49:26 CEST schrieb Chris Morgan:
> 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.

as the dts patch mentiones the odroid go2, this probably means the
Rockchip-saradc?

I very much remember that we converted the saradc to also support
triggered buffers [0] two years ago, and as I remember that worked
rather nicely on the Go-1 at least - similar hardware I think.

So it would be really helpful to provide some more explanation on
why this isn't enough for your use-case.


[0] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=4e130dc7b41348b13684f0758c26cc6cf72a3449


> Signed-off-by: Maya Matuszczyk <maccraft123mc@gmail.com>
> Signed-off-by: Chris Morgan <macromorgan@hotmail.com>
> ---
>  drivers/input/joystick/adc-joystick.c | 52 +++++++++++++++++++++------
>  1 file changed, 41 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/input/joystick/adc-joystick.c b/drivers/input/joystick/adc-joystick.c
> index 78ebca7d400a..5a28fe7b8ebc 100644
> --- a/drivers/input/joystick/adc-joystick.c
> +++ b/drivers/input/joystick/adc-joystick.c
> @@ -13,6 +13,10 @@
>  
>  #include <asm/unaligned.h>
>  
> +#define ADC_JSK_POLL_INTERVAL	16
> +#define ADC_JSK_POLL_MIN	8
> +#define ADC_JSK_POLL_MAX	32
> +
>  struct adc_joystick_axis {
>  	u32 code;
>  	s32 range[2];
> @@ -26,8 +30,21 @@ 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;
> +
> +	for (i = 0; i < joy->num_chans; i++) {
> +		iio_read_channel_raw(&joy->chans[i], &val);
> +		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;
> @@ -215,8 +232,19 @@ 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_bool(dev, "adc-joystick,polled"))
> +		joy->polled = 1;
> +
> +	if (joy->polled) {
> +		input_setup_polling(input, adc_joystick_poll);
> +		input_set_poll_interval(input, ADC_JSK_POLL_INTERVAL);
> +		input_set_min_poll_interval(input, ADC_JSK_POLL_MIN);
> +		input_set_max_poll_interval(input, ADC_JSK_POLL_MAX);
> +	} else {
> +		input->open = adc_joystick_open;
> +		input->close = adc_joystick_close;
> +	}
>  
>  	error = adc_joystick_set_axes(dev, joy);
>  	if (error)
> @@ -229,16 +257,18 @@ 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;
>