[PATCH v3 0/3] input: i.MX snvs powerkey updates

[PATCH v3 0/3] input: i.MX snvs powerkey updates

[Horia Geantă]

Hi Herbert, Dmitry,

This is a resend of v2 patches 1,5,6 that were not picked up
https://lore.kernel.org/linux-input/20200225161201.1975-1-git@andred.net
with collecting Acked-by, Reviewed-by.

I skipped Robin's Reviewed-by since I prefer avoiding misintepreting
the discussion between him and André.

Thanks,
Horia

André Draszik (3):
  dt-bindings: crypto: fsl-sec4: add snvs clock to pwrkey
  Input: snvs_pwrkey - enable snvs clock as needed
  Input: snvs_pwrkey - only IRQ_HANDLED for our own events

 .../devicetree/bindings/crypto/fsl-sec4.txt   | 17 +++++++++
 drivers/input/keyboard/snvs_pwrkey.c          | 38 ++++++++++++++++---
 2 files changed, 50 insertions(+), 5 deletions(-)

-- 
2.17.1

[PATCH v3 1/3] dt-bindings: crypto: fsl-sec4: add snvs clock to pwrkey

[Horia Geantă]

From: André Draszik <git@andred.net>

On i.MX7 and i.MX8M, the SNVS requires a clock. This is similar to the
clock bound to the SNVS RTC node, but if the SNVS RTC driver isn't
enabled, then SNVS doesn't work, and as such the pwrkey driver doesn't
work (i.e. hangs the kernel, as the clock isn't enabled).

Also see commit ec2a844ef7c1
("ARM: dts: imx7s: add snvs rtc clock")
for a similar fix.

Signed-off-by: André Draszik <git@andred.net>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Horia Geantă <horia.geanta@nxp.com>
Signed-off-by: Horia Geantă <horia.geanta@nxp.com>
---
 .../devicetree/bindings/crypto/fsl-sec4.txt     | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/Documentation/devicetree/bindings/crypto/fsl-sec4.txt b/Documentation/devicetree/bindings/crypto/fsl-sec4.txt
index 8f359f473ada..1800d57edb66 100644
--- a/Documentation/devicetree/bindings/crypto/fsl-sec4.txt
+++ b/Documentation/devicetree/bindings/crypto/fsl-sec4.txt
@@ -449,6 +449,19 @@ System ON/OFF key driver
       Value type: <phandle>
       Definition: this is phandle to the register map node.
 
+   - clocks
+      Usage: optional, required if SNVS LP requires explicit
+          enablement of clocks
+      Value type: <prop_encoded-array>
+      Definition:  a clock specifier describing the clock required for
+          enabling and disabling SNVS LP.
+
+   - clock-names
+      Usage: optional, required if SNVS LP requires explicit
+          enablement of clocks
+      Value type: <string>
+      Definition: clock name string should be "snvs-pwrkey".
+
 EXAMPLE:
 	snvs-pwrkey@020cc000 {
 		compatible = "fsl,sec-v4.0-pwrkey";
@@ -456,6 +469,8 @@ EXAMPLE:
 		interrupts = <0 4 0x4>
 	        linux,keycode = <116>; /* KEY_POWER */
 		wakeup-source;
+		clocks = <&clks IMX7D_SNVS_CLK>;
+		clock-names = "snvs-pwrkey";
 	};
 
 =====================================================================
@@ -547,6 +562,8 @@ FULL EXAMPLE
 			interrupts = <0 4 0x4>;
 			linux,keycode = <116>; /* KEY_POWER */
 			wakeup-source;
+			clocks = <&clks IMX7D_SNVS_CLK>;
+			clock-names = "snvs-pwrkey";
 		};
 	};
 
-- 
2.17.1

[PATCH v3 2/3] Input: snvs_pwrkey - enable snvs clock as needed

[Horia Geantă]

From: André Draszik <git@andred.net>

At the moment, enabling this driver without the SNVS RTC driver
being active will hang the kernel as soon as the power button
is pressed.

The reason is that in that case the SNVS isn't enabled, and
any attempt to read the SNVS registers will simply hang forever.

Ensure the clock is enabled (during the interrupt handler) to
make this driver work.

Also see commit 7f8993995410 ("drivers/rtc/rtc-snvs: add clock support")
and commit edb190cb1734
("rtc: snvs: make sure clock is enabled for interrupt handle")
for similar updates to the snvs rtc driver.

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 | 28 +++++++++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/drivers/input/keyboard/snvs_pwrkey.c b/drivers/input/keyboard/snvs_pwrkey.c
index 2f5e3ab5ed63..382d2ae82c9b 100644
--- a/drivers/input/keyboard/snvs_pwrkey.c
+++ b/drivers/input/keyboard/snvs_pwrkey.c
@@ -16,6 +16,7 @@
 #include <linux/of_address.h>
 #include <linux/platform_device.h>
 #include <linux/pm_wakeirq.h>
+#include <linux/clk.h>
 #include <linux/mfd/syscon.h>
 #include <linux/regmap.h>
 
@@ -38,6 +39,7 @@ struct pwrkey_drv_data {
 	int wakeup;
 	struct timer_list check_timer;
 	struct input_dev *input;
+	struct clk *clk;
 	u8 minor_rev;
 };
 
@@ -47,7 +49,10 @@ static void imx_imx_snvs_check_for_events(struct timer_list *t)
 	struct input_dev *input = pdata->input;
 	u32 state;
 
+	clk_enable(pdata->clk);
 	regmap_read(pdata->snvs, SNVS_HPSR_REG, &state);
+	clk_disable(pdata->clk);
+
 	state = state & SNVS_HPSR_BTN ? 1 : 0;
 
 	/* only report new event if status changed */
@@ -74,11 +79,13 @@ static irqreturn_t imx_snvs_pwrkey_interrupt(int irq, void *dev_id)
 
 	pm_wakeup_event(input->dev.parent, 0);
 
+	clk_enable(pdata->clk);
+
 	regmap_read(pdata->snvs, SNVS_LPSR_REG, &lp_status);
 	if (lp_status & SNVS_LPSR_SPO) {
 		if (pdata->minor_rev == 0) {
 			/*
-			 * The first generation i.MX6 SoCs only sends an
+			 * The first generation i.MX[6|7] SoCs only send an
 			 * interrupt on button release. To mimic power-key
 			 * usage, we'll prepend a press event.
 			 */
@@ -96,6 +103,8 @@ static irqreturn_t imx_snvs_pwrkey_interrupt(int irq, void *dev_id)
 	/* clear SPO status */
 	regmap_write(pdata->snvs, SNVS_LPSR_REG, SNVS_LPSR_SPO);
 
+	clk_disable(pdata->clk);
+
 	return IRQ_HANDLED;
 }
 
@@ -140,6 +149,23 @@ static int imx_snvs_pwrkey_probe(struct platform_device *pdev)
 	if (pdata->irq < 0)
 		return -EINVAL;
 
+	pdata->clk = devm_clk_get_optional(&pdev->dev, "snvs-pwrkey");
+	if (IS_ERR(pdata->clk))
+		return PTR_ERR(pdata->clk);
+
+	error = clk_prepare(pdata->clk);
+	if (error) {
+		dev_err(&pdev->dev, "failed to prepare the snvs clock\n");
+		return error;
+	}
+	error = devm_add_action_or_reset(&pdev->dev,
+			(void(*)(void *))clk_unprepare,
+			pdata->clk);
+	if (error) {
+		dev_err(&pdev->dev, "failed to add reset action on 'snvs-pwrkey'");
+		return error;
+	}
+
 	regmap_read(pdata->snvs, SNVS_HPVIDR1_REG, &vid);
 	pdata->minor_rev = vid & 0xff;
 
-- 
2.17.1

[PATCH v3 3/3] Input: snvs_pwrkey - only IRQ_HANDLED for our own events

[Horia Geantă]

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(-)

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)
-- 
2.17.1

Re: [PATCH v3 2/3] Input: snvs_pwrkey - enable snvs clock as needed

[Marco Felsch]

Hi,

On 20-07-23 10:43, Horia Geantă wrote:
> From: André Draszik <git@andred.net>
> 
> At the moment, enabling this driver without the SNVS RTC driver
> being active will hang the kernel as soon as the power button
> is pressed.
> 
> The reason is that in that case the SNVS isn't enabled, and
> any attempt to read the SNVS registers will simply hang forever.
> 
> Ensure the clock is enabled (during the interrupt handler) to
> make this driver work.
> 
> Also see commit 7f8993995410 ("drivers/rtc/rtc-snvs: add clock support")
> and commit edb190cb1734
> ("rtc: snvs: make sure clock is enabled for interrupt handle")
> for similar updates to the snvs rtc driver.
> 
> 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 | 28 +++++++++++++++++++++++++++-
>  1 file changed, 27 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/input/keyboard/snvs_pwrkey.c b/drivers/input/keyboard/snvs_pwrkey.c
> index 2f5e3ab5ed63..382d2ae82c9b 100644
> --- a/drivers/input/keyboard/snvs_pwrkey.c
> +++ b/drivers/input/keyboard/snvs_pwrkey.c
> @@ -16,6 +16,7 @@
>  #include <linux/of_address.h>
>  #include <linux/platform_device.h>
>  #include <linux/pm_wakeirq.h>
> +#include <linux/clk.h>
>  #include <linux/mfd/syscon.h>
>  #include <linux/regmap.h>
>  
> @@ -38,6 +39,7 @@ struct pwrkey_drv_data {
>  	int wakeup;
>  	struct timer_list check_timer;
>  	struct input_dev *input;
> +	struct clk *clk;
>  	u8 minor_rev;
>  };
>  
> @@ -47,7 +49,10 @@ static void imx_imx_snvs_check_for_events(struct timer_list *t)
>  	struct input_dev *input = pdata->input;
>  	u32 state;
>  
> +	clk_enable(pdata->clk);
>  	regmap_read(pdata->snvs, SNVS_HPSR_REG, &state);
> +	clk_disable(pdata->clk);
> +
>  	state = state & SNVS_HPSR_BTN ? 1 : 0;
>  
>  	/* only report new event if status changed */
> @@ -74,11 +79,13 @@ static irqreturn_t imx_snvs_pwrkey_interrupt(int irq, void *dev_id)
>  
>  	pm_wakeup_event(input->dev.parent, 0);
>  
> +	clk_enable(pdata->clk);
> +
>  	regmap_read(pdata->snvs, SNVS_LPSR_REG, &lp_status);
>  	if (lp_status & SNVS_LPSR_SPO) {
>  		if (pdata->minor_rev == 0) {
>  			/*
> -			 * The first generation i.MX6 SoCs only sends an
> +			 * The first generation i.MX[6|7] SoCs only send an
>  			 * interrupt on button release. To mimic power-key
>  			 * usage, we'll prepend a press event.
>  			 */
> @@ -96,6 +103,8 @@ static irqreturn_t imx_snvs_pwrkey_interrupt(int irq, void *dev_id)
>  	/* clear SPO status */
>  	regmap_write(pdata->snvs, SNVS_LPSR_REG, SNVS_LPSR_SPO);
>  
> +	clk_disable(pdata->clk);

I'm not so happy about clk_enable/disable() during the interrupt
routine since those routines should be handled fast. Since we assume
that the clock is always on I would rather call clk_prepare_enable()
during probe() and keep the clock on.

> +
>  	return IRQ_HANDLED;
>  }
>  
> @@ -140,6 +149,23 @@ static int imx_snvs_pwrkey_probe(struct platform_device *pdev)
>  	if (pdata->irq < 0)
>  		return -EINVAL;
>  
> +	pdata->clk = devm_clk_get_optional(&pdev->dev, "snvs-pwrkey");
> +	if (IS_ERR(pdata->clk))
> +		return PTR_ERR(pdata->clk);
> +
> +	error = clk_prepare(pdata->clk);
> +	if (error) {
> +		dev_err(&pdev->dev, "failed to prepare the snvs clock\n");
> +		return error;
> +	}
> +	error = devm_add_action_or_reset(&pdev->dev,
> +			(void(*)(void *))clk_unprepare,
> +			pdata->clk);

I'm not a fan about those casts. However, the intentation should be
fixed.

Regards,
  Marco

> +	if (error) {
> +		dev_err(&pdev->dev, "failed to add reset action on 'snvs-pwrkey'");
> +		return error;
> +	}
> +
>  	regmap_read(pdata->snvs, SNVS_HPVIDR1_REG, &vid);
>  	pdata->minor_rev = vid & 0xff;

Re: [PATCH v3 3/3] Input: snvs_pwrkey - only IRQ_HANDLED for our own events

[Marco Felsch]

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

Re: [PATCH v3 2/3] Input: snvs_pwrkey - enable snvs clock as needed

[Dmitry Torokhov]

On Wed, Jul 29, 2020 at 09:33:23AM +0200, Marco Felsch wrote:
> Hi,
> 
> On 20-07-23 10:43, Horia Geantă wrote:
> > From: André Draszik <git@andred.net>
> > 
> > At the moment, enabling this driver without the SNVS RTC driver
> > being active will hang the kernel as soon as the power button
> > is pressed.
> > 
> > The reason is that in that case the SNVS isn't enabled, and
> > any attempt to read the SNVS registers will simply hang forever.
> > 
> > Ensure the clock is enabled (during the interrupt handler) to
> > make this driver work.
> > 
> > Also see commit 7f8993995410 ("drivers/rtc/rtc-snvs: add clock support")
> > and commit edb190cb1734
> > ("rtc: snvs: make sure clock is enabled for interrupt handle")
> > for similar updates to the snvs rtc driver.
> > 
> > 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 | 28 +++++++++++++++++++++++++++-
> >  1 file changed, 27 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/input/keyboard/snvs_pwrkey.c b/drivers/input/keyboard/snvs_pwrkey.c
> > index 2f5e3ab5ed63..382d2ae82c9b 100644
> > --- a/drivers/input/keyboard/snvs_pwrkey.c
> > +++ b/drivers/input/keyboard/snvs_pwrkey.c
> > @@ -16,6 +16,7 @@
> >  #include <linux/of_address.h>
> >  #include <linux/platform_device.h>
> >  #include <linux/pm_wakeirq.h>
> > +#include <linux/clk.h>
> >  #include <linux/mfd/syscon.h>
> >  #include <linux/regmap.h>
> >  
> > @@ -38,6 +39,7 @@ struct pwrkey_drv_data {
> >  	int wakeup;
> >  	struct timer_list check_timer;
> >  	struct input_dev *input;
> > +	struct clk *clk;
> >  	u8 minor_rev;
> >  };
> >  
> > @@ -47,7 +49,10 @@ static void imx_imx_snvs_check_for_events(struct timer_list *t)
> >  	struct input_dev *input = pdata->input;
> >  	u32 state;
> >  
> > +	clk_enable(pdata->clk);
> >  	regmap_read(pdata->snvs, SNVS_HPSR_REG, &state);
> > +	clk_disable(pdata->clk);
> > +
> >  	state = state & SNVS_HPSR_BTN ? 1 : 0;
> >  
> >  	/* only report new event if status changed */
> > @@ -74,11 +79,13 @@ static irqreturn_t imx_snvs_pwrkey_interrupt(int irq, void *dev_id)
> >  
> >  	pm_wakeup_event(input->dev.parent, 0);
> >  
> > +	clk_enable(pdata->clk);
> > +
> >  	regmap_read(pdata->snvs, SNVS_LPSR_REG, &lp_status);
> >  	if (lp_status & SNVS_LPSR_SPO) {
> >  		if (pdata->minor_rev == 0) {
> >  			/*
> > -			 * The first generation i.MX6 SoCs only sends an
> > +			 * The first generation i.MX[6|7] SoCs only send an
> >  			 * interrupt on button release. To mimic power-key
> >  			 * usage, we'll prepend a press event.
> >  			 */
> > @@ -96,6 +103,8 @@ static irqreturn_t imx_snvs_pwrkey_interrupt(int irq, void *dev_id)
> >  	/* clear SPO status */
> >  	regmap_write(pdata->snvs, SNVS_LPSR_REG, SNVS_LPSR_SPO);
> >  
> > +	clk_disable(pdata->clk);
> 
> I'm not so happy about clk_enable/disable() during the interrupt
> routine since those routines should be handled fast. Since we assume
> that the clock is always oni

We do? I thought that the fact that clock might be off is the root of
the problem.

> I would rather call clk_prepare_enable()
> during probe() and keep the clock on.

clk_enable() must not sleep and is supposed to be lightweight. This
interrupt I believe is supposed to be infrequent, so having it here
should be fine and might save us some power.

> 
> > +
> >  	return IRQ_HANDLED;
> >  }
> >  
> > @@ -140,6 +149,23 @@ static int imx_snvs_pwrkey_probe(struct platform_device *pdev)
> >  	if (pdata->irq < 0)
> >  		return -EINVAL;
> >  
> > +	pdata->clk = devm_clk_get_optional(&pdev->dev, "snvs-pwrkey");
> > +	if (IS_ERR(pdata->clk))
> > +		return PTR_ERR(pdata->clk);
> > +
> > +	error = clk_prepare(pdata->clk);
> > +	if (error) {
> > +		dev_err(&pdev->dev, "failed to prepare the snvs clock\n");
> > +		return error;
> > +	}
> > +	error = devm_add_action_or_reset(&pdev->dev,
> > +			(void(*)(void *))clk_unprepare,
> > +			pdata->clk);
> 
> I'm not a fan about those casts. However, the intentation should be
> fixed.

Yes, can we please create a proper function for this (or maybe we will
finally get devm clk API?).

Thanks.

-- 
Dmitry

Re: [PATCH v3 3/3] Input: snvs_pwrkey - only IRQ_HANDLED for our own events

[Dmitry Torokhov]

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.

-- 
Dmitry

Re: [PATCH v3 2/3] Input: snvs_pwrkey - enable snvs clock as needed

[Marco Felsch]

Hi Dmitry,

On 20-07-29 23:04, Dmitry Torokhov wrote:
> On Wed, Jul 29, 2020 at 09:33:23AM +0200, Marco Felsch wrote:
> > Hi,
> > 
> > On 20-07-23 10:43, Horia Geantă wrote:
> > > From: André Draszik <git@andred.net>
> > > 
> > > At the moment, enabling this driver without the SNVS RTC driver
> > > being active will hang the kernel as soon as the power button
> > > is pressed.
> > > 
> > > The reason is that in that case the SNVS isn't enabled, and
> > > any attempt to read the SNVS registers will simply hang forever.
> > > 
> > > Ensure the clock is enabled (during the interrupt handler) to
> > > make this driver work.
> > > 
> > > Also see commit 7f8993995410 ("drivers/rtc/rtc-snvs: add clock support")
> > > and commit edb190cb1734
> > > ("rtc: snvs: make sure clock is enabled for interrupt handle")
> > > for similar updates to the snvs rtc driver.
> > > 
> > > 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 | 28 +++++++++++++++++++++++++++-
> > >  1 file changed, 27 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/input/keyboard/snvs_pwrkey.c b/drivers/input/keyboard/snvs_pwrkey.c
> > > index 2f5e3ab5ed63..382d2ae82c9b 100644
> > > --- a/drivers/input/keyboard/snvs_pwrkey.c
> > > +++ b/drivers/input/keyboard/snvs_pwrkey.c
> > > @@ -16,6 +16,7 @@
> > >  #include <linux/of_address.h>
> > >  #include <linux/platform_device.h>
> > >  #include <linux/pm_wakeirq.h>
> > > +#include <linux/clk.h>
> > >  #include <linux/mfd/syscon.h>
> > >  #include <linux/regmap.h>
> > >  
> > > @@ -38,6 +39,7 @@ struct pwrkey_drv_data {
> > >  	int wakeup;
> > >  	struct timer_list check_timer;
> > >  	struct input_dev *input;
> > > +	struct clk *clk;
> > >  	u8 minor_rev;
> > >  };
> > >  
> > > @@ -47,7 +49,10 @@ static void imx_imx_snvs_check_for_events(struct timer_list *t)
> > >  	struct input_dev *input = pdata->input;
> > >  	u32 state;
> > >  
> > > +	clk_enable(pdata->clk);
> > >  	regmap_read(pdata->snvs, SNVS_HPSR_REG, &state);
> > > +	clk_disable(pdata->clk);
> > > +
> > >  	state = state & SNVS_HPSR_BTN ? 1 : 0;
> > >  
> > >  	/* only report new event if status changed */
> > > @@ -74,11 +79,13 @@ static irqreturn_t imx_snvs_pwrkey_interrupt(int irq, void *dev_id)
> > >  
> > >  	pm_wakeup_event(input->dev.parent, 0);
> > >  
> > > +	clk_enable(pdata->clk);
> > > +
> > >  	regmap_read(pdata->snvs, SNVS_LPSR_REG, &lp_status);
> > >  	if (lp_status & SNVS_LPSR_SPO) {
> > >  		if (pdata->minor_rev == 0) {
> > >  			/*
> > > -			 * The first generation i.MX6 SoCs only sends an
> > > +			 * The first generation i.MX[6|7] SoCs only send an
> > >  			 * interrupt on button release. To mimic power-key
> > >  			 * usage, we'll prepend a press event.
> > >  			 */
> > > @@ -96,6 +103,8 @@ static irqreturn_t imx_snvs_pwrkey_interrupt(int irq, void *dev_id)
> > >  	/* clear SPO status */
> > >  	regmap_write(pdata->snvs, SNVS_LPSR_REG, SNVS_LPSR_SPO);
> > >  
> > > +	clk_disable(pdata->clk);
> > 
> > I'm not so happy about clk_enable/disable() during the interrupt
> > routine since those routines should be handled fast. Since we assume
> > that the clock is always oni
> 
> We do? I thought that the fact that clock might be off is the root of
> the problem.

Currently yes else the driver would never work. I thought so at least
after reading the commit message. But after checking the imx6qdl I
found that the imx6qdl has no clock-gate for the SNVS module. I think
Horia had Problems on a imx7 device since he adapted the comment to
cover the imx7. Which makes more sense since the imx7 has a clock gate
but the commit message is wrong. After checking the device-tree's in
mainline all imx7 and imx8 devices specify the "snvs-pwrkey" clock so
this is a new feature and they need the clock. So IMHO for those devices
a clock should be required and not optional.

> > I would rather call clk_prepare_enable()
> > during probe() and keep the clock on.
> 
> clk_enable() must not sleep and is supposed to be lightweight. This
> interrupt I believe is supposed to be infrequent, so having it here
> should be fine and might save us some power.

Didn't know that clk_enable()/clk_disable() never sleeps and yes it
should be infrequent triggered. I don't think that we can save a
measureable amount of power since this is Low-Power IP clocked by a
low-power clock. However, this was just my point of view.

> > > +
> > >  	return IRQ_HANDLED;
> > >  }
> > >  
> > > @@ -140,6 +149,23 @@ static int imx_snvs_pwrkey_probe(struct platform_device *pdev)
> > >  	if (pdata->irq < 0)
> > >  		return -EINVAL;
> > >  
> > > +	pdata->clk = devm_clk_get_optional(&pdev->dev, "snvs-pwrkey");
> > > +	if (IS_ERR(pdata->clk))
> > > +		return PTR_ERR(pdata->clk);
> > > +
> > > +	error = clk_prepare(pdata->clk);
> > > +	if (error) {
> > > +		dev_err(&pdev->dev, "failed to prepare the snvs clock\n");
> > > +		return error;
> > > +	}
> > > +	error = devm_add_action_or_reset(&pdev->dev,
> > > +			(void(*)(void *))clk_unprepare,
> > > +			pdata->clk);
> > 
> > I'm not a fan about those casts. However, the intentation should be
> > fixed.
> 
> Yes, can we please create a proper function for this (or maybe we will
> finally get devm clk API?).

devm_clk API +1 :)

Regards,
  Marco

Re: [PATCH v3 3/3] Input: snvs_pwrkey - only IRQ_HANDLED for our own events

[Marco Felsch]

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