Re: [PATCH V2 2/2] rc: gpio-ir-recv: add timeout on idle

[Sean Young <sean@mess.org>]

On Mon, Sep 21, 2015 at 12:08:44PM -0700, Eric Nelson wrote:
> Many decoders require a trailing space (period without IR illumination)
> to be delivered before completing a decode.
> 
> Since the gpio-ir-recv driver only delivers events on gpio transitions,
> a single IR symbol (caused by a quick touch on an IR remote) will not
> be properly decoded without the use of a timer to flush the tail end
> state of the IR receiver.
> 
> This patch initializes and uses a timer and the timeout field of rcdev
> to complete the stream and allow decode.
> 
> The timeout can be overridden through the use of the LIRC_SET_REC_TIMEOUT
> ioctl.

Thanks, this is much nicer.

> Signed-off-by: Eric Nelson <eric@nelint.com>
> ---
>  drivers/media/rc/gpio-ir-recv.c | 22 ++++++++++++++++++++++
>  1 file changed, 22 insertions(+)
> 
> diff --git a/drivers/media/rc/gpio-ir-recv.c b/drivers/media/rc/gpio-ir-recv.c
> index 7dbc9ca..d3b216a 100644
> --- a/drivers/media/rc/gpio-ir-recv.c
> +++ b/drivers/media/rc/gpio-ir-recv.c
> @@ -30,6 +30,7 @@ struct gpio_rc_dev {
>  	struct rc_dev *rcdev;
>  	int gpio_nr;
>  	bool active_low;
> +	struct timer_list flush_timer;
>  };
>  
>  #ifdef CONFIG_OF
> @@ -93,12 +94,26 @@ static irqreturn_t gpio_ir_recv_irq(int irq, void *dev_id)
>  	if (rc < 0)
>  		goto err_get_value;
>  
> +	mod_timer(&gpio_dev->flush_timer,
> +		  jiffies + nsecs_to_jiffies(gpio_dev->rcdev->timeout));
> +
>  	ir_raw_event_handle(gpio_dev->rcdev);
>  
>  err_get_value:
>  	return IRQ_HANDLED;
>  }
>  
> +static void flush_timer(unsigned long arg)
> +{
> +	struct gpio_rc_dev *gpio_dev = (struct gpio_rc_dev *)arg;
> +	DEFINE_IR_RAW_EVENT(ev);
> +
> +	ev.timeout = true;
> +	ev.duration =  gpio_dev->rcdev->timeout;

Nitpick: two spaces, checkpatch would have found this.

> +	ir_raw_event_store(gpio_dev->rcdev, &ev);
> +	ir_raw_event_handle(gpio_dev->rcdev);
> +}
> +
>  static int gpio_ir_recv_probe(struct platform_device *pdev)
>  {
>  	struct gpio_rc_dev *gpio_dev;
> @@ -144,6 +159,9 @@ static int gpio_ir_recv_probe(struct platform_device *pdev)
>  	rcdev->input_id.version = 0x0100;
>  	rcdev->dev.parent = &pdev->dev;
>  	rcdev->driver_name = GPIO_IR_DRIVER_NAME;
> +	rcdev->min_timeout = 1;
> +	rcdev->timeout = IR_DEFAULT_TIMEOUT;
> +	rcdev->max_timeout = 10 * IR_DEFAULT_TIMEOUT;
>  	if (pdata->allowed_protos)
>  		rcdev->allowed_protocols = pdata->allowed_protos;
>  	else
> @@ -154,6 +172,10 @@ static int gpio_ir_recv_probe(struct platform_device *pdev)
>  	gpio_dev->gpio_nr = pdata->gpio_nr;
>  	gpio_dev->active_low = pdata->active_low;
>  
> +	init_timer(&gpio_dev->flush_timer);
> +	gpio_dev->flush_timer.function = flush_timer;
> +	gpio_dev->flush_timer.data = (unsigned long)gpio_dev;


You could use "setup_timer(&gpio_dev->flush_timer, flush_timer, (unsigned long)gpio_dev);" here.


> +
>  	rc = gpio_request(pdata->gpio_nr, "gpio-ir-recv");
>  	if (rc < 0)
>  		goto err_gpio_request;

You'll need a "del_timer_sync(&gpio_dev->flush_timer);" in 
gpio_ir_recv_remove() or you'll have a race on remove.


Sean