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Input: gpio-keys - use hrtimer for release timer

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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: Paul Cercueil <paul@crapouillou.net>
Link: https://lore.kernel.org/r/20210307222240.380583-2-paul@crapouillou.net
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
This commit is contained in:
Paul Cercueil 2021-03-21 16:06:34 -07:00 • committed by Dmitry Torokhov
parent 36a8fc6fa2
commit 019002f20c
1 changed files with 16 additions and 11 deletions
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27
drivers/input/keyboard/gpio_keys.c
View file

@ -8,6 +8,7 @@
#include <linux/module.h> #include <linux/module.h>
#include <linux/hrtimer.h>
#include <linux/init.h> #include <linux/init.h>
#include <linux/fs.h> #include <linux/fs.h>
#include <linux/interrupt.h> #include <linux/interrupt.h>
@ -36,7 +37,7 @@ struct gpio_button_data {
unsigned short *code; unsigned short *code;
struct timer_list release_timer; struct hrtimer release_timer;
unsigned int release_delay; /* in msecs, for IRQ-only buttons */ unsigned int release_delay; /* in msecs, for IRQ-only buttons */
struct delayed_work work; struct delayed_work work;
@ -146,7 +147,7 @@ static void gpio_keys_disable_button(struct gpio_button_data *bdata)
if (bdata->gpiod) if (bdata->gpiod)
cancel_delayed_work_sync(&bdata->work); cancel_delayed_work_sync(&bdata->work);
else else
del_timer_sync(&bdata->release_timer); hrtimer_cancel(&bdata->release_timer);
bdata->disabled = true; bdata->disabled = true;
} }
@ -415,19 +416,20 @@ static irqreturn_t gpio_keys_gpio_isr(int irq, void *dev_id)
return IRQ_HANDLED; 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; struct input_dev *input = bdata->input;
unsigned long flags;
spin_lock_irqsave(&bdata->lock, flags);
if (bdata->key_pressed) { if (bdata->key_pressed) {
input_event(input, EV_KEY, *bdata->code, 0); input_event(input, EV_KEY, *bdata->code, 0);
input_sync(input); input_sync(input);
bdata->key_pressed = false; 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) 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) if (bdata->release_delay)
mod_timer(&bdata->release_timer, hrtimer_start(&bdata->release_timer,
jiffies + msecs_to_jiffies(bdata->release_delay)); ms_to_ktime(bdata->release_delay),
HRTIMER_MODE_REL_HARD);
out: out:
spin_unlock_irqrestore(&bdata->lock, flags); spin_unlock_irqrestore(&bdata->lock, flags);
return IRQ_HANDLED; return IRQ_HANDLED;
@ -471,7 +474,7 @@ static void gpio_keys_quiesce_key(void *data)
if (bdata->gpiod) if (bdata->gpiod)
cancel_delayed_work_sync(&bdata->work); cancel_delayed_work_sync(&bdata->work);
else else
del_timer_sync(&bdata->release_timer); hrtimer_cancel(&bdata->release_timer);
} }
static int gpio_keys_setup_key(struct platform_device *pdev, 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; 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; isr = gpio_keys_irq_isr;
irqflags = 0; irqflags = 0;