[PATCH 0/3] A few fixes to sprd watchdog driver

[PATCH 0/3] A few fixes to sprd watchdog driver

[Chunyan Zhang]

From: Chunyan Zhang <chunyan.zhang@unisoc.com>

A few issues about sprd watchdog driver were found recently, this
patchset would fix them.

Lingling Xu (3):
  watchdog: sprd: should not disable watchdog in resume
  watchdog: sprd: change timeout value from 1000 to 2000
  watchdog: sprd: check busy bit before kick watchdog

 drivers/watchdog/sprd_wdt.c | 38 +++++++++++++++++--------------------
 1 file changed, 17 insertions(+), 21 deletions(-)

-- 
2.20.1

[PATCH 1/3] watchdog: sprd: should not disable watchdog in resume

[Chunyan Zhang]

From: Lingling Xu <ling_ling.xu@unisoc.com>

Don't disable watchdog in resume process, otherwise system would crash
once kick watchdog.

Fixes: 477603467009 ("watchdog: Add Spreadtrum watchdog driver")
Signed-off-by: Lingling Xu <ling_ling.xu@unisoc.com>
Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com>
---
 drivers/watchdog/sprd_wdt.c | 9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/drivers/watchdog/sprd_wdt.c b/drivers/watchdog/sprd_wdt.c
index 65cb55f3916f..f3c90b4afead 100644
--- a/drivers/watchdog/sprd_wdt.c
+++ b/drivers/watchdog/sprd_wdt.c
@@ -345,15 +345,10 @@ static int __maybe_unused sprd_wdt_pm_resume(struct device *dev)
 	if (ret)
 		return ret;
 
-	if (watchdog_active(&wdt->wdd)) {
+	if (watchdog_active(&wdt->wdd))
 		ret = sprd_wdt_start(&wdt->wdd);
-		if (ret) {
-			sprd_wdt_disable(wdt);
-			return ret;
-		}
-	}
 
-	return 0;
+	return ret;
 }
 
 static const struct dev_pm_ops sprd_wdt_pm_ops = {
-- 
2.20.1

[PATCH 2/3] watchdog: sprd: change timeout value from 1000 to 2000

[Chunyan Zhang]

From: Lingling Xu <ling_ling.xu@unisoc.com>

Because cpu_relax() takes different time on different SoCs, for some rare
cases, it would take more than 1000 cycles for waitting load operation
finished. The result of many times testing verified that changing the
timeout value to 2000 can solve the issue.

Fixes: 477603467009 ("watchdog: Add Spreadtrum watchdog driver")
Signed-off-by: Lingling Xu <ling_ling.xu@unisoc.com>
Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com>
---
 drivers/watchdog/sprd_wdt.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/watchdog/sprd_wdt.c b/drivers/watchdog/sprd_wdt.c
index f3c90b4afead..4f2a8c6d6485 100644
--- a/drivers/watchdog/sprd_wdt.c
+++ b/drivers/watchdog/sprd_wdt.c
@@ -53,7 +53,7 @@
 
 #define SPRD_WDT_CNT_HIGH_SHIFT		16
 #define SPRD_WDT_LOW_VALUE_MASK		GENMASK(15, 0)
-#define SPRD_WDT_LOAD_TIMEOUT		1000
+#define SPRD_WDT_LOAD_TIMEOUT		2000
 
 struct sprd_wdt {
 	void __iomem *base;
-- 
2.20.1

[PATCH 3/3] watchdog: sprd: check busy bit before kick watchdog

[Chunyan Zhang]

From: Lingling Xu <ling_ling.xu@unisoc.com>

As the specification described, checking busy bit must be done before kick
watchdog.

Fixes: 477603467009 ("watchdog: Add Spreadtrum watchdog driver")
Signed-off-by: Lingling Xu <ling_ling.xu@unisoc.com>
Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com>
---
 drivers/watchdog/sprd_wdt.c | 27 ++++++++++++++-------------
 1 file changed, 14 insertions(+), 13 deletions(-)

diff --git a/drivers/watchdog/sprd_wdt.c b/drivers/watchdog/sprd_wdt.c
index 4f2a8c6d6485..14071c66ff49 100644
--- a/drivers/watchdog/sprd_wdt.c
+++ b/drivers/watchdog/sprd_wdt.c
@@ -108,20 +108,8 @@ static int sprd_wdt_load_value(struct sprd_wdt *wdt, u32 timeout,
 	u32 tmr_step = timeout * SPRD_WDT_CNT_STEP;
 	u32 prtmr_step = pretimeout * SPRD_WDT_CNT_STEP;
 
-	sprd_wdt_unlock(wdt->base);
-	writel_relaxed((tmr_step >> SPRD_WDT_CNT_HIGH_SHIFT) &
-		      SPRD_WDT_LOW_VALUE_MASK, wdt->base + SPRD_WDT_LOAD_HIGH);
-	writel_relaxed((tmr_step & SPRD_WDT_LOW_VALUE_MASK),
-		       wdt->base + SPRD_WDT_LOAD_LOW);
-	writel_relaxed((prtmr_step >> SPRD_WDT_CNT_HIGH_SHIFT) &
-			SPRD_WDT_LOW_VALUE_MASK,
-		       wdt->base + SPRD_WDT_IRQ_LOAD_HIGH);
-	writel_relaxed(prtmr_step & SPRD_WDT_LOW_VALUE_MASK,
-		       wdt->base + SPRD_WDT_IRQ_LOAD_LOW);
-	sprd_wdt_lock(wdt->base);
-
 	/*
-	 * Waiting the load value operation done,
+	 * Waiting the last load value operation done,
 	 * it needs two or three RTC clock cycles.
 	 */
 	do {
@@ -134,6 +122,19 @@ static int sprd_wdt_load_value(struct sprd_wdt *wdt, u32 timeout,
 
 	if (delay_cnt >= SPRD_WDT_LOAD_TIMEOUT)
 		return -EBUSY;
+
+	sprd_wdt_unlock(wdt->base);
+	writel_relaxed((tmr_step >> SPRD_WDT_CNT_HIGH_SHIFT) &
+		      SPRD_WDT_LOW_VALUE_MASK, wdt->base + SPRD_WDT_LOAD_HIGH);
+	writel_relaxed((tmr_step & SPRD_WDT_LOW_VALUE_MASK),
+		       wdt->base + SPRD_WDT_LOAD_LOW);
+	writel_relaxed((prtmr_step >> SPRD_WDT_CNT_HIGH_SHIFT) &
+			SPRD_WDT_LOW_VALUE_MASK,
+		       wdt->base + SPRD_WDT_IRQ_LOAD_HIGH);
+	writel_relaxed(prtmr_step & SPRD_WDT_LOW_VALUE_MASK,
+		       wdt->base + SPRD_WDT_IRQ_LOAD_LOW);
+	sprd_wdt_lock(wdt->base);
+
 	return 0;
 }
 
-- 
2.20.1

Re: [PATCH 1/3] watchdog: sprd: should not disable watchdog in resume

[Guenter Roeck]

On 10/26/20 1:09 AM, Chunyan Zhang wrote:
> From: Lingling Xu <ling_ling.xu@unisoc.com>
> 
> Don't disable watchdog in resume process, otherwise system would crash
> once kick watchdog.
> 

This is a bit misleading: It is only disabled if the attempt to start it
has failed. Was this observed in practice ? If so, it might make sense
to identify and fix the underlying problem instead of trying to work
around it (or is this addressed with the second patch of the series ?)

Anyway, the patch itself is fine.

Reviewed-by: Guenter Roeck <linux@roeck-us.net>

Thanks,
Guenter

> Fixes: 477603467009 ("watchdog: Add Spreadtrum watchdog driver")
> Signed-off-by: Lingling Xu <ling_ling.xu@unisoc.com>
> Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com>
> ---
>  drivers/watchdog/sprd_wdt.c | 9 ++-------
>  1 file changed, 2 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/watchdog/sprd_wdt.c b/drivers/watchdog/sprd_wdt.c
> index 65cb55f3916f..f3c90b4afead 100644
> --- a/drivers/watchdog/sprd_wdt.c
> +++ b/drivers/watchdog/sprd_wdt.c
> @@ -345,15 +345,10 @@ static int __maybe_unused sprd_wdt_pm_resume(struct device *dev)
>  	if (ret)
>  		return ret;
>  
> -	if (watchdog_active(&wdt->wdd)) {
> +	if (watchdog_active(&wdt->wdd))
>  		ret = sprd_wdt_start(&wdt->wdd);
> -		if (ret) {
> -			sprd_wdt_disable(wdt);
> -			return ret;
> -		}
> -	}
>  
> -	return 0;
> +	return ret;
>  }
>  
>  static const struct dev_pm_ops sprd_wdt_pm_ops = {
> 

Re: [PATCH 2/3] watchdog: sprd: change timeout value from 1000 to 2000

[Guenter Roeck]

On 10/26/20 1:09 AM, Chunyan Zhang wrote:
> From: Lingling Xu <ling_ling.xu@unisoc.com>
> 
> Because cpu_relax() takes different time on different SoCs, for some rare
> cases, it would take more than 1000 cycles for waitting load operation

waiting

> finished. The result of many times testing verified that changing the
> timeout value to 2000 can solve the issue.
> 

This is just a kludge that doesn't address the underlying problem.
As the wait loop states, "Waiting the load value operation done,
it needs two or three RTC clock cycles". This means the loop
should wait for a maximum number of clock cycles, and not run
as hot loop. If we assume that clk_get_rate() returns the clock
frequency, that frequency can be used to determine how long this
needs to be retried. It might also make sense - depending on how
long this actually takes - to use usleep_range() instead of
cpu_relax() to avoid the hot loop.

Guenter

> Fixes: 477603467009 ("watchdog: Add Spreadtrum watchdog driver")
> Signed-off-by: Lingling Xu <ling_ling.xu@unisoc.com>
> Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com>
> ---
>  drivers/watchdog/sprd_wdt.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/watchdog/sprd_wdt.c b/drivers/watchdog/sprd_wdt.c
> index f3c90b4afead..4f2a8c6d6485 100644
> --- a/drivers/watchdog/sprd_wdt.c
> +++ b/drivers/watchdog/sprd_wdt.c
> @@ -53,7 +53,7 @@
>  
>  #define SPRD_WDT_CNT_HIGH_SHIFT		16
>  #define SPRD_WDT_LOW_VALUE_MASK		GENMASK(15, 0)
> -#define SPRD_WDT_LOAD_TIMEOUT		1000
> +#define SPRD_WDT_LOAD_TIMEOUT		2000
>  
>  struct sprd_wdt {
>  	void __iomem *base;
> 

Re: [PATCH 3/3] watchdog: sprd: check busy bit before kick watchdog

[Guenter Roeck]

On 10/26/20 1:09 AM, Chunyan Zhang wrote:
> From: Lingling Xu <ling_ling.xu@unisoc.com>
> 
> As the specification described, checking busy bit must be done before kick
> watchdog.
> 

That is a key functional change: So far the code checked if a value
was accepted after loading it. That is no longer the case. Effectively,
with this change, the _next_ operation will now check if the previous
operation was accepted. Is this intentional ?

Also, does this really solve a problem, or is it just an optimization ?
By checking for busy prior to an operation instead of after it the only
real difference is that the busy check will most likely succeed immediately
because enough time has passed since the last write.

Ultimately it is your call how you want to handle this, but I think the
impact should be spelled out.

Guenter

> Fixes: 477603467009 ("watchdog: Add Spreadtrum watchdog driver")
> Signed-off-by: Lingling Xu <ling_ling.xu@unisoc.com>
> Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com>
> ---
>  drivers/watchdog/sprd_wdt.c | 27 ++++++++++++++-------------
>  1 file changed, 14 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/watchdog/sprd_wdt.c b/drivers/watchdog/sprd_wdt.c
> index 4f2a8c6d6485..14071c66ff49 100644
> --- a/drivers/watchdog/sprd_wdt.c
> +++ b/drivers/watchdog/sprd_wdt.c
> @@ -108,20 +108,8 @@ static int sprd_wdt_load_value(struct sprd_wdt *wdt, u32 timeout,
>  	u32 tmr_step = timeout * SPRD_WDT_CNT_STEP;
>  	u32 prtmr_step = pretimeout * SPRD_WDT_CNT_STEP;
>  
> -	sprd_wdt_unlock(wdt->base);
> -	writel_relaxed((tmr_step >> SPRD_WDT_CNT_HIGH_SHIFT) &
> -		      SPRD_WDT_LOW_VALUE_MASK, wdt->base + SPRD_WDT_LOAD_HIGH);
> -	writel_relaxed((tmr_step & SPRD_WDT_LOW_VALUE_MASK),
> -		       wdt->base + SPRD_WDT_LOAD_LOW);
> -	writel_relaxed((prtmr_step >> SPRD_WDT_CNT_HIGH_SHIFT) &
> -			SPRD_WDT_LOW_VALUE_MASK,
> -		       wdt->base + SPRD_WDT_IRQ_LOAD_HIGH);
> -	writel_relaxed(prtmr_step & SPRD_WDT_LOW_VALUE_MASK,
> -		       wdt->base + SPRD_WDT_IRQ_LOAD_LOW);
> -	sprd_wdt_lock(wdt->base);
> -
>  	/*
> -	 * Waiting the load value operation done,
> +	 * Waiting the last load value operation done,
>  	 * it needs two or three RTC clock cycles.
>  	 */
>  	do {
> @@ -134,6 +122,19 @@ static int sprd_wdt_load_value(struct sprd_wdt *wdt, u32 timeout,
>  
>  	if (delay_cnt >= SPRD_WDT_LOAD_TIMEOUT)
>  		return -EBUSY;
> +
> +	sprd_wdt_unlock(wdt->base);
> +	writel_relaxed((tmr_step >> SPRD_WDT_CNT_HIGH_SHIFT) &
> +		      SPRD_WDT_LOW_VALUE_MASK, wdt->base + SPRD_WDT_LOAD_HIGH);
> +	writel_relaxed((tmr_step & SPRD_WDT_LOW_VALUE_MASK),
> +		       wdt->base + SPRD_WDT_LOAD_LOW);
> +	writel_relaxed((prtmr_step >> SPRD_WDT_CNT_HIGH_SHIFT) &
> +			SPRD_WDT_LOW_VALUE_MASK,
> +		       wdt->base + SPRD_WDT_IRQ_LOAD_HIGH);
> +	writel_relaxed(prtmr_step & SPRD_WDT_LOW_VALUE_MASK,
> +		       wdt->base + SPRD_WDT_IRQ_LOAD_LOW);
> +	sprd_wdt_lock(wdt->base);
> +
>  	return 0;
>  }
>  
> 

Re: [PATCH 3/3] watchdog: sprd: check busy bit before kick watchdog

[Chunyan Zhang]

On Mon, 26 Oct 2020 at 22:44, Guenter Roeck <linux@roeck-us.net> wrote:
>
> On 10/26/20 1:09 AM, Chunyan Zhang wrote:
> > From: Lingling Xu <ling_ling.xu@unisoc.com>
> >
> > As the specification described, checking busy bit must be done before kick
> > watchdog.
> >
>
> That is a key functional change: So far the code checked if a value
> was accepted after loading it. That is no longer the case. Effectively,
> with this change, the _next_ operation will now check if the previous
> operation was accepted. Is this intentional ?

Yes, the busy bit indicates whether the previous operation is done, so
we have to make sure the last loading completed (the busy bit is not
set) before new loading.

The spec says that this bit is set after a new loading, and would last
2 or 3 RTC clock cycles.

>
> Also, does this really solve a problem, or is it just an optimization ?
> By checking for busy prior to an operation instead of after it the only
> real difference is that the busy check will most likely succeed immediately
> because enough time has passed since the last write.
>
> Ultimately it is your call how you want to handle this, but I think the
> impact should be spelled out.

Ok, I will add more details in the commit message.

Many thanks for the review!

Chunyan

>
> Guenter
>
> > Fixes: 477603467009 ("watchdog: Add Spreadtrum watchdog driver")
> > Signed-off-by: Lingling Xu <ling_ling.xu@unisoc.com>
> > Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com>
> > ---
> >  drivers/watchdog/sprd_wdt.c | 27 ++++++++++++++-------------
> >  1 file changed, 14 insertions(+), 13 deletions(-)
> >
> > diff --git a/drivers/watchdog/sprd_wdt.c b/drivers/watchdog/sprd_wdt.c
> > index 4f2a8c6d6485..14071c66ff49 100644
> > --- a/drivers/watchdog/sprd_wdt.c
> > +++ b/drivers/watchdog/sprd_wdt.c
> > @@ -108,20 +108,8 @@ static int sprd_wdt_load_value(struct sprd_wdt *wdt, u32 timeout,
> >       u32 tmr_step = timeout * SPRD_WDT_CNT_STEP;
> >       u32 prtmr_step = pretimeout * SPRD_WDT_CNT_STEP;
> >
> > -     sprd_wdt_unlock(wdt->base);
> > -     writel_relaxed((tmr_step >> SPRD_WDT_CNT_HIGH_SHIFT) &
> > -                   SPRD_WDT_LOW_VALUE_MASK, wdt->base + SPRD_WDT_LOAD_HIGH);
> > -     writel_relaxed((tmr_step & SPRD_WDT_LOW_VALUE_MASK),
> > -                    wdt->base + SPRD_WDT_LOAD_LOW);
> > -     writel_relaxed((prtmr_step >> SPRD_WDT_CNT_HIGH_SHIFT) &
> > -                     SPRD_WDT_LOW_VALUE_MASK,
> > -                    wdt->base + SPRD_WDT_IRQ_LOAD_HIGH);
> > -     writel_relaxed(prtmr_step & SPRD_WDT_LOW_VALUE_MASK,
> > -                    wdt->base + SPRD_WDT_IRQ_LOAD_LOW);
> > -     sprd_wdt_lock(wdt->base);
> > -
> >       /*
> > -      * Waiting the load value operation done,
> > +      * Waiting the last load value operation done,
> >        * it needs two or three RTC clock cycles.
> >        */
> >       do {
> > @@ -134,6 +122,19 @@ static int sprd_wdt_load_value(struct sprd_wdt *wdt, u32 timeout,
> >
> >       if (delay_cnt >= SPRD_WDT_LOAD_TIMEOUT)
> >               return -EBUSY;
> > +
> > +     sprd_wdt_unlock(wdt->base);
> > +     writel_relaxed((tmr_step >> SPRD_WDT_CNT_HIGH_SHIFT) &
> > +                   SPRD_WDT_LOW_VALUE_MASK, wdt->base + SPRD_WDT_LOAD_HIGH);
> > +     writel_relaxed((tmr_step & SPRD_WDT_LOW_VALUE_MASK),
> > +                    wdt->base + SPRD_WDT_LOAD_LOW);
> > +     writel_relaxed((prtmr_step >> SPRD_WDT_CNT_HIGH_SHIFT) &
> > +                     SPRD_WDT_LOW_VALUE_MASK,
> > +                    wdt->base + SPRD_WDT_IRQ_LOAD_HIGH);
> > +     writel_relaxed(prtmr_step & SPRD_WDT_LOW_VALUE_MASK,
> > +                    wdt->base + SPRD_WDT_IRQ_LOAD_LOW);
> > +     sprd_wdt_lock(wdt->base);
> > +
> >       return 0;
> >  }
> >
> >
>

Re: [PATCH 2/3] watchdog: sprd: change timeout value from 1000 to 2000

[Chunyan Zhang]

On Mon, 26 Oct 2020 at 22:36, Guenter Roeck <linux@roeck-us.net> wrote:
>
> On 10/26/20 1:09 AM, Chunyan Zhang wrote:
> > From: Lingling Xu <ling_ling.xu@unisoc.com>
> >
> > Because cpu_relax() takes different time on different SoCs, for some rare
> > cases, it would take more than 1000 cycles for waitting load operation
>
> waiting

Ok.

>
> > finished. The result of many times testing verified that changing the
> > timeout value to 2000 can solve the issue.
> >
>
> This is just a kludge that doesn't address the underlying problem.
> As the wait loop states, "Waiting the load value operation done,
> it needs two or three RTC clock cycles". This means the loop
> should wait for a maximum number of clock cycles, and not run
> as hot loop. If we assume that clk_get_rate() returns the clock
> frequency, that frequency can be used to determine how long this
> needs to be retried. It might also make sense - depending on how
> long this actually takes - to use usleep_range() instead of
> cpu_relax() to avoid the hot loop.

Agree, using usleep_range() instead makes more sense, I will look into that.

Thanks for your review.

Chunyan

>
> Guenter
>
> > Fixes: 477603467009 ("watchdog: Add Spreadtrum watchdog driver")
> > Signed-off-by: Lingling Xu <ling_ling.xu@unisoc.com>
> > Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com>
> > ---
> >  drivers/watchdog/sprd_wdt.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/watchdog/sprd_wdt.c b/drivers/watchdog/sprd_wdt.c
> > index f3c90b4afead..4f2a8c6d6485 100644
> > --- a/drivers/watchdog/sprd_wdt.c
> > +++ b/drivers/watchdog/sprd_wdt.c
> > @@ -53,7 +53,7 @@
> >
> >  #define SPRD_WDT_CNT_HIGH_SHIFT              16
> >  #define SPRD_WDT_LOW_VALUE_MASK              GENMASK(15, 0)
> > -#define SPRD_WDT_LOAD_TIMEOUT                1000
> > +#define SPRD_WDT_LOAD_TIMEOUT                2000
> >
> >  struct sprd_wdt {
> >       void __iomem *base;
> >
>

Re: [PATCH 1/3] watchdog: sprd: should not disable watchdog in resume

[Chunyan Zhang]

On Mon, 26 Oct 2020 at 22:27, Guenter Roeck <linux@roeck-us.net> wrote:
>
> On 10/26/20 1:09 AM, Chunyan Zhang wrote:
> > From: Lingling Xu <ling_ling.xu@unisoc.com>
> >
> > Don't disable watchdog in resume process, otherwise system would crash
> > once kick watchdog.
> >
>
> This is a bit misleading: It is only disabled if the attempt to start it
> has failed. Was this observed in practice ? If so, it might make sense
> to identify and fix the underlying problem instead of trying to work
> around it (or is this addressed with the second patch of the series ?)

Yes, I think the root cause of this problem was like what I explained
in the 3rd patch in this series.
Lingling found there was something wrong in sprd_wdt_pm_resume() when
debugging that issue, then we had this patch.

>
> Anyway, the patch itself is fine.
>
> Reviewed-by: Guenter Roeck <linux@roeck-us.net>

Thanks,
Chunyan

>
> Thanks,
> Guenter
>
> > Fixes: 477603467009 ("watchdog: Add Spreadtrum watchdog driver")
> > Signed-off-by: Lingling Xu <ling_ling.xu@unisoc.com>
> > Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com>
> > ---
> >  drivers/watchdog/sprd_wdt.c | 9 ++-------
> >  1 file changed, 2 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/watchdog/sprd_wdt.c b/drivers/watchdog/sprd_wdt.c
> > index 65cb55f3916f..f3c90b4afead 100644
> > --- a/drivers/watchdog/sprd_wdt.c
> > +++ b/drivers/watchdog/sprd_wdt.c
> > @@ -345,15 +345,10 @@ static int __maybe_unused sprd_wdt_pm_resume(struct device *dev)
> >       if (ret)
> >               return ret;
> >
> > -     if (watchdog_active(&wdt->wdd)) {
> > +     if (watchdog_active(&wdt->wdd))
> >               ret = sprd_wdt_start(&wdt->wdd);
> > -             if (ret) {
> > -                     sprd_wdt_disable(wdt);
> > -                     return ret;
> > -             }
> > -     }
> >
> > -     return 0;
> > +     return ret;
> >  }
> >
> >  static const struct dev_pm_ops sprd_wdt_pm_ops = {
> >
>