[v3,3/3] Input: snvs_pwrkey - only IRQ_HANDLED for our own events
diff mbox series

Message ID 20200723074314.3304-4-horia.geanta@nxp.com
State New
Headers show
Series
  • input: i.MX snvs powerkey updates
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Commit Message

Horia Geantă July 23, 2020, 7:43 a.m. UTC
From: André Draszik <git@andred.net>

The snvs_pwrkey shares the SNVS LPSR status register with the snvs_rtc.

This driver here should only return IRQ_HANDLED if the status register
indicates that the event we're handling in the irq handler was genuinely
intended for this driver. Otheriwse the interrupt subsystem will
assume the interrupt was handled successfully even though it wasn't
at all.

Signed-off-by: André Draszik <git@andred.net>
Reviewed-by: Horia Geantă <horia.geanta@nxp.com>
Signed-off-by: Horia Geantă <horia.geanta@nxp.com>
---
 drivers/input/keyboard/snvs_pwrkey.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

Comments

Marco Felsch July 29, 2020, 7:55 a.m. UTC | #1
Hi,

On 20-07-23 10:43, Horia Geantă wrote:
> From: André Draszik <git@andred.net>
> 
> The snvs_pwrkey shares the SNVS LPSR status register with the snvs_rtc.
> 
> This driver here should only return IRQ_HANDLED if the status register
> indicates that the event we're handling in the irq handler was genuinely
> intended for this driver. Otheriwse the interrupt subsystem will
> assume the interrupt was handled successfully even though it wasn't
> at all.

After checking the RM and the imx6qdl.dtsi I'm not very sure that this
is right since the snvs-powerkey has a seperate irq-line. So we can be
sure that this irq is for us. If this is the case we don't need to check
the SNVS_LPSR_REG instead we only need to clear it.

Regards,
  Marco
Dmitry Torokhov July 30, 2020, 6:06 a.m. UTC | #2
Hi Marco,

On Wed, Jul 29, 2020 at 09:55:13AM +0200, Marco Felsch wrote:
> Hi,
> 
> On 20-07-23 10:43, Horia Geantă wrote:
> > From: André Draszik <git@andred.net>
> > 
> > The snvs_pwrkey shares the SNVS LPSR status register with the snvs_rtc.
> > 
> > This driver here should only return IRQ_HANDLED if the status register
> > indicates that the event we're handling in the irq handler was genuinely
> > intended for this driver. Otheriwse the interrupt subsystem will
> > assume the interrupt was handled successfully even though it wasn't
> > at all.
> 
> After checking the RM and the imx6qdl.dtsi I'm not very sure that this
> is right since the snvs-powerkey has a seperate irq-line. So we can be
> sure that this irq is for us. If this is the case we don't need to check
> the SNVS_LPSR_REG instead we only need to clear it.

Wouldn't we want to know if for some reason we get spurious interrupts?

Thanks.
Marco Felsch July 30, 2020, 8:59 a.m. UTC | #3
Hi Dmitry,

On 20-07-29 23:06, Dmitry Torokhov wrote:
> Hi Marco,
> 
> On Wed, Jul 29, 2020 at 09:55:13AM +0200, Marco Felsch wrote:
> > Hi,
> > 
> > On 20-07-23 10:43, Horia Geantă wrote:
> > > From: André Draszik <git@andred.net>
> > > 
> > > The snvs_pwrkey shares the SNVS LPSR status register with the snvs_rtc.
> > > 
> > > This driver here should only return IRQ_HANDLED if the status register
> > > indicates that the event we're handling in the irq handler was genuinely
> > > intended for this driver. Otheriwse the interrupt subsystem will
> > > assume the interrupt was handled successfully even though it wasn't
> > > at all.
> > 
> > After checking the RM and the imx6qdl.dtsi I'm not very sure that this
> > is right since the snvs-powerkey has a seperate irq-line. So we can be
> > sure that this irq is for us. If this is the case we don't need to check
> > the SNVS_LPSR_REG instead we only need to clear it.
> 
> Wouldn't we want to know if for some reason we get spurious interrupts?

We could check the bit at the very begin of the IRQ and return early but
according the RM this should never happen. Anyway you're right HW is
never bug free.

Regards,
  Marco

> Thanks.
> 
> -- 
> Dmitry

Patch
diff mbox series

diff --git a/drivers/input/keyboard/snvs_pwrkey.c b/drivers/input/keyboard/snvs_pwrkey.c
index 382d2ae82c9b..980867886b34 100644
--- a/drivers/input/keyboard/snvs_pwrkey.c
+++ b/drivers/input/keyboard/snvs_pwrkey.c
@@ -82,7 +82,9 @@  static irqreturn_t imx_snvs_pwrkey_interrupt(int irq, void *dev_id)
 	clk_enable(pdata->clk);
 
 	regmap_read(pdata->snvs, SNVS_LPSR_REG, &lp_status);
-	if (lp_status & SNVS_LPSR_SPO) {
+	lp_status &= SNVS_LPSR_SPO;
+
+	if (lp_status) {
 		if (pdata->minor_rev == 0) {
 			/*
 			 * The first generation i.MX[6|7] SoCs only send an
@@ -98,14 +100,14 @@  static irqreturn_t imx_snvs_pwrkey_interrupt(int irq, void *dev_id)
 			mod_timer(&pdata->check_timer,
 			          jiffies + msecs_to_jiffies(DEBOUNCE_TIME));
 		}
-	}
 
-	/* clear SPO status */
-	regmap_write(pdata->snvs, SNVS_LPSR_REG, SNVS_LPSR_SPO);
+		/* clear SPO status */
+		regmap_write(pdata->snvs, SNVS_LPSR_REG, SNVS_LPSR_SPO);
+	}
 
 	clk_disable(pdata->clk);
 
-	return IRQ_HANDLED;
+	return lp_status ? IRQ_HANDLED : IRQ_NONE;
 }
 
 static void imx_snvs_pwrkey_act(void *pdata)