We want to be able to report the input event as soon as the debounce
delay elapsed. However, the current code does not really ensure that,
as it uses the jiffies-based schedule_delayed_work() API. With a small
enough HZ value (HZ <= 100), this results in some input events being
lost, when a key is quickly pressed then released (on a human's time
scale).
Switching to hrtimers fixes this issue, and will work even on extremely
low HZ values (tested at HZ=24).
Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
---
Notes:
v2: HRTIMER_MODE_REL_SOFT -> HRTIMER_MODE_REL
drivers/input/keyboard/gpio_keys.c | 33 +++++++++++++++---------------
1 file changed, 17 insertions(+), 16 deletions(-)
diff --git a/drivers/input/keyboard/gpio_keys.c b/drivers/input/keyboard/gpio_keys.c
index 4b92f49decef..566e7950fcef 100644
--- a/drivers/input/keyboard/gpio_keys.c
+++ b/drivers/input/keyboard/gpio_keys.c
@@ -22,7 +22,6 @@
#include <linux/platform_device.h>
#include <linux/input.h>
#include <linux/gpio_keys.h>
-#include <linux/workqueue.h>
#include <linux/gpio.h>
#include <linux/gpio/consumer.h>
#include <linux/of.h>
@@ -40,7 +39,7 @@ struct gpio_button_data {
struct hrtimer release_timer;
unsigned int release_delay; /* in msecs, for IRQ-only buttons */
- struct delayed_work work;
+ struct hrtimer debounce_timer;
unsigned int software_debounce; /* in msecs, for GPIO-driven buttons */
unsigned int irq;
@@ -145,7 +144,7 @@ static void gpio_keys_disable_button(struct gpio_button_data *bdata)
disable_irq(bdata->irq);
if (bdata->gpiod)
- cancel_delayed_work_sync(&bdata->work);
+ hrtimer_cancel(&bdata->debounce_timer);
else
hrtimer_cancel(&bdata->release_timer);
@@ -376,16 +375,19 @@ static void gpio_keys_gpio_report_event(struct gpio_button_data *bdata)
}
}
-static void gpio_keys_gpio_work_func(struct work_struct *work)
+static enum hrtimer_restart gpio_keys_debounce_timer(struct hrtimer *t)
{
- struct gpio_button_data *bdata =
- container_of(work, struct gpio_button_data, work.work);
+ struct gpio_button_data *bdata = container_of(t,
+ struct gpio_button_data,
+ debounce_timer);
gpio_keys_gpio_report_event(bdata);
input_sync(bdata->input);
if (bdata->button->wakeup)
pm_relax(bdata->input->dev.parent);
+
+ return HRTIMER_NORESTART;
}
static irqreturn_t gpio_keys_gpio_isr(int irq, void *dev_id)
@@ -409,9 +411,9 @@ static irqreturn_t gpio_keys_gpio_isr(int irq, void *dev_id)
}
}
- mod_delayed_work(system_wq,
- &bdata->work,
- msecs_to_jiffies(bdata->software_debounce));
+ hrtimer_start(&bdata->debounce_timer,
+ ms_to_ktime(bdata->software_debounce),
+ HRTIMER_MODE_REL);
return IRQ_HANDLED;
}
@@ -472,7 +474,7 @@ static void gpio_keys_quiesce_key(void *data)
struct gpio_button_data *bdata = data;
if (bdata->gpiod)
- cancel_delayed_work_sync(&bdata->work);
+ hrtimer_cancel(&bdata->debounce_timer);
else
hrtimer_cancel(&bdata->release_timer);
}
@@ -562,11 +564,13 @@ static int gpio_keys_setup_key(struct platform_device *pdev,
bdata->irq = irq;
}
- INIT_DELAYED_WORK(&bdata->work, gpio_keys_gpio_work_func);
-
isr = gpio_keys_gpio_isr;
irqflags = IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING;
+ hrtimer_init(&bdata->debounce_timer,
+ CLOCK_REALTIME, HRTIMER_MODE_REL);
+ bdata->debounce_timer.function = gpio_keys_debounce_timer;
+
switch (button->wakeup_event_action) {
case EV_ACT_ASSERTED:
bdata->wakeup_trigger_type = active_low ?
@@ -615,10 +619,7 @@ static int gpio_keys_setup_key(struct platform_device *pdev,
*bdata->code = button->code;
input_set_capability(input, button->type ?: EV_KEY, *bdata->code);
- /*
- * Install custom action to cancel release timer and
- * workqueue item.
- */
+ /* Install custom action to cancel timers. */
error = devm_add_action(dev, gpio_keys_quiesce_key, bdata);
if (error) {
dev_err(dev, "failed to register quiesce action, error: %d\n",
--
2.30.1
