Re: [PATCH v5 4/4] Input: snvs_pwrkey - add press event reporting to avoid event loss during suspend

[Frank Li]

On Wed, Jul 15, 2026 at 05:33:54PM +0800, joy.zou@xxxxxxxxxxx wrote:
> From: Joy Zou <joy.zou@xxxxxxx>
>
> The driver implements debounce protection using a timer-based mechanism:
> when a key interrupt occurs, a timer is scheduled to verify the key state
> after DEBOUNCE_TIME before reporting the event. This works well during
> normal operation.
>
> However, key press events can be lost during system resume on platforms
> like i.MX8MQ-EVK because:
> 1. During the no_irq resume phase, PCIe driver restoration can take up to
> 200ms with IRQs disabled.
> 2. The power key interrupt remains pending during the no_irq phase.
> 3. If the key is released before IRQs are re-enabled, the timer eventually
> runs but sees the key as released and skips reporting the event.
>
> To prevent event loss during system suspend, set a pending_press flag in
> the interrupt handler and report the press event from the timer callback
> when the flag is set. This avoids out-of-order event delivery and keeps
> the existing timer-based debounce mechanism for normal operation.
>
> Signed-off-by: Joy Zou <joy.zou@xxxxxxx>
> ---
> Changes for v5:
> 1. Replace SIMPLE_DEV_PM_OPS with DEFINE_SIMPLE_DEV_PM_OPS and remove
>    __maybe_unused from suspend/resume callbacks.
> 2. Use pm_ptr() to wrap pm_ops pointer in platform_driver.
> 3. Replace suspended flag check in interrupt handler with a pending_press
>    latch: set pending_press in hardirq context, consume and report the
>    press event from the timer callback in softirq context.
>
> Changes for v3:
> 1. Add spinlock for pdata->keystate and pdata->suspended per AI review
>    comments.
> 2. Replace hardcode value 1 with local variable keystate in input_report_key()
>    under suspended.
>
> Changes for v2:
> 1. Add a boolean variable suspended and PM callback functions to replace
>    the use of the is_suspended field per AI review comments.
> 2. Move event report handle to else branch in suspended state, since the
>    pdata->minor_rev == 0 branch has no debounce detection per AI review
>    comments.
> 3. Modify the commit message.
> ---

Reviewed-by: Frank Li <Frank.Li@xxxxxxx>

>  drivers/input/keyboard/snvs_pwrkey.c | 72 ++++++++++++++++++++++++++++++++++--
>  1 file changed, 68 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/input/keyboard/snvs_pwrkey.c b/drivers/input/keyboard/snvs_pwrkey.c
> index cbe44a38d2b3..970c7d65bd57 100644
> --- a/drivers/input/keyboard/snvs_pwrkey.c
> +++ b/drivers/input/keyboard/snvs_pwrkey.c
> @@ -39,6 +39,9 @@ struct pwrkey_drv_data {
>  	int keycode;
>  	int keystate;  /* 1:pressed */
>  	int wakeup;
> +	bool suspended;     /* Track suspend state */
> +	bool pending_press; /* Key pressed during suspend, report from timer callback */
> +	spinlock_t lock;    /* Protects keystate, suspended and pending_press */
>  	struct timer_list check_timer;
>  	struct input_dev *input;
>  	u8 minor_rev;
> @@ -49,14 +52,38 @@ static void imx_imx_snvs_check_for_events(struct timer_list *t)
>  	struct pwrkey_drv_data *pdata = timer_container_of(pdata, t,
>  							   check_timer);
>  	struct input_dev *input = pdata->input;
> +	bool state_changed = false;
> +	bool pending_press;
>  	u32 state;
>
>  	regmap_read(pdata->snvs, SNVS_HPSR_REG, &state);
>  	state = state & SNVS_HPSR_BTN ? 1 : 0;
>
> -	/* only report new event if status changed */
> -	if (state ^ pdata->keystate) {
> -		pdata->keystate = state;
> +	scoped_guard(spinlock_irqsave, &pdata->lock) {
> +		pending_press = pdata->pending_press;
> +		if (pending_press) {
> +			pdata->pending_press = false;
> +			pdata->keystate = 1;
> +		}
> +		/* only report new event if status changed */
> +		if (state ^ pdata->keystate) {
> +			pdata->keystate = state;
> +			state_changed = true;
> +		}
> +	}
> +
> +	/*
> +	 * Report a press event latched during suspend. If the key is still
> +	 * held, state_changed will be 0 (keystate already set to 1 above),
> +	 * so no duplicate press is reported. If already released,
> +	 * state_changed will fire next to report the release.
> +	 */
> +	if (pending_press) {
> +		input_report_key(input, pdata->keycode, 1);
> +		input_sync(input);
> +	}
> +
> +	if (state_changed) {
>  		input_event(input, EV_KEY, pdata->keycode, state);
>  		input_sync(input);
>  		pm_relax(pdata->input->dev.parent);
> @@ -92,8 +119,17 @@ static irqreturn_t imx_snvs_pwrkey_interrupt(int irq, void *dev_id)
>  			input_sync(input);
>  			pm_relax(input->dev.parent);
>  		} else {
> +			/*
> +			 * If the key is pressed during suspend, latch it so
> +			 * the timer callback can report the press event in
> +			 * softirq context, avoiding out-of-order events.
> +			 */
> +			scoped_guard(spinlock_irqsave, &pdata->lock) {
> +				if (pdata->suspended)
> +					pdata->pending_press = true;
> +			}
>  			mod_timer(&pdata->check_timer,
> -			          jiffies + msecs_to_jiffies(DEBOUNCE_TIME));
> +				  jiffies + msecs_to_jiffies(DEBOUNCE_TIME));
>  		}
>  	}
>
> @@ -151,6 +187,7 @@ static int imx_snvs_pwrkey_probe(struct platform_device *pdev)
>  	if (pdata->irq < 0)
>  		return pdata->irq;
>
> +	spin_lock_init(&pdata->lock);
>  	error = of_property_read_u32(np, "power-off-time-sec", &val);
>  	if (!error) {
>  		switch (val) {
> @@ -217,6 +254,32 @@ static int imx_snvs_pwrkey_probe(struct platform_device *pdev)
>  	return 0;
>  }
>
> +static int imx_snvs_pwrkey_suspend(struct device *dev)
> +{
> +	struct platform_device *pdev = to_platform_device(dev);
> +	struct pwrkey_drv_data *pdata = platform_get_drvdata(pdev);
> +
> +	scoped_guard(spinlock_irqsave, &pdata->lock)
> +		pdata->suspended = true;
> +
> +	return 0;
> +}
> +
> +static int imx_snvs_pwrkey_resume(struct device *dev)
> +{
> +	struct platform_device *pdev = to_platform_device(dev);
> +	struct pwrkey_drv_data *pdata = platform_get_drvdata(pdev);
> +
> +	scoped_guard(spinlock_irqsave, &pdata->lock)
> +		pdata->suspended = false;
> +
> +	return 0;
> +}
> +
> +static DEFINE_SIMPLE_DEV_PM_OPS(imx_snvs_pwrkey_pm_ops,
> +				imx_snvs_pwrkey_suspend,
> +				imx_snvs_pwrkey_resume);
> +
>  static const struct of_device_id imx_snvs_pwrkey_ids[] = {
>  	{ .compatible = "fsl,sec-v4.0-pwrkey" },
>  	{ /* sentinel */ }
> @@ -227,6 +290,7 @@ static struct platform_driver imx_snvs_pwrkey_driver = {
>  	.driver = {
>  		.name = "snvs_pwrkey",
>  		.of_match_table = imx_snvs_pwrkey_ids,
> +		.pm = pm_ptr(&imx_snvs_pwrkey_pm_ops),
>  	},
>  	.probe = imx_snvs_pwrkey_probe,
>  };
>
> --
> 2.34.1
>
>