Commit 019002f2 authored by Paul Cercueil's avatar Paul Cercueil Committed by Dmitry Torokhov
Browse files

Input: gpio-keys - use hrtimer for release timer 



Dealing with input, timing is important; if the button should be
released in one millisecond, then it should be done in one millisecond
and not a hundred milliseconds.

Therefore, the standard timer API is not really suitable for this task.

Convert the gpio-keys driver to use a hrtimer instead of the standard
timer to address this issue.

Note that by using a hard IRQ for the hrtimer callback, we can get rid
of the spin_lock_irqsave() and spin_unlock_irqrestore().

Signed-off-by: default avatarPaul Cercueil <paul@crapouillou.net>
Link: https://lore.kernel.org/r/20210307222240.380583-2-paul@crapouillou.net


Signed-off-by: default avatarDmitry Torokhov <dmitry.torokhov@gmail.com>
parent 36a8fc6f

drivers/input/keyboard/gpio_keys.c

+16 −11
Original line number Diff line number Diff line
@@ -8,6 +8,7 @@ 


#include <linux/module.h>



#include <linux/hrtimer.h>

#include <linux/init.h>

#include <linux/fs.h>

#include <linux/interrupt.h>
@@ -36,7 +37,7 @@ struct gpio_button_data { 


	unsigned short *code;



	struct timer_list release_timer;

	struct hrtimer release_timer;

	unsigned int release_delay;	/* in msecs, for IRQ-only buttons */



	struct delayed_work work;
@@ -146,7 +147,7 @@ static void gpio_keys_disable_button(struct gpio_button_data *bdata) 
		if (bdata->gpiod)

			cancel_delayed_work_sync(&bdata->work);

		else

			del_timer_sync(&bdata->release_timer);

			hrtimer_cancel(&bdata->release_timer);



		bdata->disabled = true;

	}
@@ -415,19 +416,20 @@ static irqreturn_t gpio_keys_gpio_isr(int irq, void *dev_id) 
	return IRQ_HANDLED;

}



static void gpio_keys_irq_timer(struct timer_list *t)

static enum hrtimer_restart gpio_keys_irq_timer(struct hrtimer *t)

{

	struct gpio_button_data *bdata = from_timer(bdata, t, release_timer);

	struct gpio_button_data *bdata = container_of(t,

						      struct gpio_button_data,

						      release_timer);

	struct input_dev *input = bdata->input;

	unsigned long flags;



	spin_lock_irqsave(&bdata->lock, flags);

	if (bdata->key_pressed) {

		input_event(input, EV_KEY, *bdata->code, 0);

		input_sync(input);

		bdata->key_pressed = false;

	}

	spin_unlock_irqrestore(&bdata->lock, flags);



	return HRTIMER_NORESTART;

}



static irqreturn_t gpio_keys_irq_isr(int irq, void *dev_id)
@@ -457,8 +459,9 @@ static irqreturn_t gpio_keys_irq_isr(int irq, void *dev_id) 
	}



	if (bdata->release_delay)

		mod_timer(&bdata->release_timer,

			jiffies + msecs_to_jiffies(bdata->release_delay));

		hrtimer_start(&bdata->release_timer,

			      ms_to_ktime(bdata->release_delay),

			      HRTIMER_MODE_REL_HARD);

out:

	spin_unlock_irqrestore(&bdata->lock, flags);

	return IRQ_HANDLED;
@@ -471,7 +474,7 @@ static void gpio_keys_quiesce_key(void *data) 
	if (bdata->gpiod)

		cancel_delayed_work_sync(&bdata->work);

	else

		del_timer_sync(&bdata->release_timer);

		hrtimer_cancel(&bdata->release_timer);

}



static int gpio_keys_setup_key(struct platform_device *pdev,
@@ -595,7 +598,9 @@ static int gpio_keys_setup_key(struct platform_device *pdev, 
		}



		bdata->release_delay = button->debounce_interval;

		timer_setup(&bdata->release_timer, gpio_keys_irq_timer, 0);

		hrtimer_init(&bdata->release_timer,

			     CLOCK_REALTIME, HRTIMER_MODE_REL_HARD);

		bdata->release_timer.function = gpio_keys_irq_timer;



		isr = gpio_keys_irq_isr;

		irqflags = 0;