[PATCH] watchdog: qcom: Remove incorrect usage of QCOM_WDT_ENABLE_IRQ

[PATCH] watchdog: qcom: Remove incorrect usage of QCOM_WDT_ENABLE_IRQ

[Sai Prakash Ranjan]

As per register documentation, QCOM_WDT_ENABLE_IRQ which is BIT(1)
of watchdog control register is wakeup interrupt enable bit and
not related to bark interrupt at all, BIT(0) is used for that.
So remove incorrect usage of this bit when supporting bark irq for
pre-timeout notification. Currently with this bit set and bark
interrupt specified, pre-timeout notification and/or watchdog
reset/bite does not occur.

Fixes: 36375491a439 ("watchdog: qcom: support pre-timeout when the bark irq is available")
Cc: stable@vger.kernel.org
Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
---

Reading the conversations from when qcom pre-timeout support was
added [1], Bjorn already had mentioned it was not right to touch this
bit, not sure which SoC the pre-timeout was tested on at that time,
but I have tested this on SDM845, SM8150, SC7180 and watchdog bark
and bite does not occur with enabling this bit with the bark irq
specified in DT.

[1] https://lore.kernel.org/linux-watchdog/20190906174009.GC11938@tuxbook-pro/

---
 drivers/watchdog/qcom-wdt.c | 13 +------------
 1 file changed, 1 insertion(+), 12 deletions(-)

diff --git a/drivers/watchdog/qcom-wdt.c b/drivers/watchdog/qcom-wdt.c
index 7cf0f2ec649b..e38a87ffe5f5 100644
--- a/drivers/watchdog/qcom-wdt.c
+++ b/drivers/watchdog/qcom-wdt.c
@@ -22,7 +22,6 @@ enum wdt_reg {
 };
 
 #define QCOM_WDT_ENABLE		BIT(0)
-#define QCOM_WDT_ENABLE_IRQ	BIT(1)
 
 static const u32 reg_offset_data_apcs_tmr[] = {
 	[WDT_RST] = 0x38,
@@ -63,16 +62,6 @@ struct qcom_wdt *to_qcom_wdt(struct watchdog_device *wdd)
 	return container_of(wdd, struct qcom_wdt, wdd);
 }
 
-static inline int qcom_get_enable(struct watchdog_device *wdd)
-{
-	int enable = QCOM_WDT_ENABLE;
-
-	if (wdd->pretimeout)
-		enable |= QCOM_WDT_ENABLE_IRQ;
-
-	return enable;
-}
-
 static irqreturn_t qcom_wdt_isr(int irq, void *arg)
 {
 	struct watchdog_device *wdd = arg;
@@ -91,7 +80,7 @@ static int qcom_wdt_start(struct watchdog_device *wdd)
 	writel(1, wdt_addr(wdt, WDT_RST));
 	writel(bark * wdt->rate, wdt_addr(wdt, WDT_BARK_TIME));
 	writel(wdd->timeout * wdt->rate, wdt_addr(wdt, WDT_BITE_TIME));
-	writel(qcom_get_enable(wdd), wdt_addr(wdt, WDT_EN));
+	writel(QCOM_WDT_ENABLE, wdt_addr(wdt, WDT_EN));
 	return 0;
 }
 
-- 
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Re: [PATCH] watchdog: qcom: Remove incorrect usage of QCOM_WDT_ENABLE_IRQ

[Guenter Roeck]

On 1/26/21 7:02 AM, Sai Prakash Ranjan wrote:
> As per register documentation, QCOM_WDT_ENABLE_IRQ which is BIT(1)
> of watchdog control register is wakeup interrupt enable bit and
> not related to bark interrupt at all, BIT(0) is used for that.
> So remove incorrect usage of this bit when supporting bark irq for
> pre-timeout notification. Currently with this bit set and bark
> interrupt specified, pre-timeout notification and/or watchdog
> reset/bite does not occur.
> 
> Fixes: 36375491a439 ("watchdog: qcom: support pre-timeout when the bark irq is available")
> Cc: stable@vger.kernel.org
> Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>

Assuming that pretimeout _does_ work with this patch applied,

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

> ---
> 
> Reading the conversations from when qcom pre-timeout support was
> added [1], Bjorn already had mentioned it was not right to touch this
> bit, not sure which SoC the pre-timeout was tested on at that time,
> but I have tested this on SDM845, SM8150, SC7180 and watchdog bark
> and bite does not occur with enabling this bit with the bark irq
> specified in DT.
> 
> [1] https://lore.kernel.org/linux-watchdog/20190906174009.GC11938@tuxbook-pro/
> 
> ---
>  drivers/watchdog/qcom-wdt.c | 13 +------------
>  1 file changed, 1 insertion(+), 12 deletions(-)
> 
> diff --git a/drivers/watchdog/qcom-wdt.c b/drivers/watchdog/qcom-wdt.c
> index 7cf0f2ec649b..e38a87ffe5f5 100644
> --- a/drivers/watchdog/qcom-wdt.c
> +++ b/drivers/watchdog/qcom-wdt.c
> @@ -22,7 +22,6 @@ enum wdt_reg {
>  };
>  
>  #define QCOM_WDT_ENABLE		BIT(0)
> -#define QCOM_WDT_ENABLE_IRQ	BIT(1)
>  
>  static const u32 reg_offset_data_apcs_tmr[] = {
>  	[WDT_RST] = 0x38,
> @@ -63,16 +62,6 @@ struct qcom_wdt *to_qcom_wdt(struct watchdog_device *wdd)
>  	return container_of(wdd, struct qcom_wdt, wdd);
>  }
>  
> -static inline int qcom_get_enable(struct watchdog_device *wdd)
> -{
> -	int enable = QCOM_WDT_ENABLE;
> -
> -	if (wdd->pretimeout)
> -		enable |= QCOM_WDT_ENABLE_IRQ;
> -
> -	return enable;
> -}
> -
>  static irqreturn_t qcom_wdt_isr(int irq, void *arg)
>  {
>  	struct watchdog_device *wdd = arg;
> @@ -91,7 +80,7 @@ static int qcom_wdt_start(struct watchdog_device *wdd)
>  	writel(1, wdt_addr(wdt, WDT_RST));
>  	writel(bark * wdt->rate, wdt_addr(wdt, WDT_BARK_TIME));
>  	writel(wdd->timeout * wdt->rate, wdt_addr(wdt, WDT_BITE_TIME));
> -	writel(qcom_get_enable(wdd), wdt_addr(wdt, WDT_EN));
> +	writel(QCOM_WDT_ENABLE, wdt_addr(wdt, WDT_EN));
>  	return 0;
>  }
>  
> 

Re: [PATCH] watchdog: qcom: Remove incorrect usage of QCOM_WDT_ENABLE_IRQ

[Sai Prakash Ranjan]

On 2021-01-26 20:53, Guenter Roeck wrote:
> On 1/26/21 7:02 AM, Sai Prakash Ranjan wrote:
>> As per register documentation, QCOM_WDT_ENABLE_IRQ which is BIT(1)
>> of watchdog control register is wakeup interrupt enable bit and
>> not related to bark interrupt at all, BIT(0) is used for that.
>> So remove incorrect usage of this bit when supporting bark irq for
>> pre-timeout notification. Currently with this bit set and bark
>> interrupt specified, pre-timeout notification and/or watchdog
>> reset/bite does not occur.
>> 
>> Fixes: 36375491a439 ("watchdog: qcom: support pre-timeout when the 
>> bark irq is available")
>> Cc: stable@vger.kernel.org
>> Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
> 
> Assuming that pretimeout _does_ work with this patch applied,
> 
> Reviewed-by: Guenter Roeck <linux@roeck-us.net>
> 

Thanks Guenter. Yes I have patchset ready and tested [1] on 4
different SoCs on which pretimeout works with this patch and without
this, watchdog functionality would be broken on all those platforms
and possibly more(the ones I couldn't get access to) if we add bark
irq to the watchdog DT node.

[1] https://lore.kernel.org/patchwork/cover/1371270/

Thanks,
Sai

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member
of Code Aurora Forum, hosted by The Linux Foundation

Re: [PATCH] watchdog: qcom: Remove incorrect usage of QCOM_WDT_ENABLE_IRQ

[Stephen Boyd]

Quoting Sai Prakash Ranjan (2021-01-26 07:02:41)
> As per register documentation, QCOM_WDT_ENABLE_IRQ which is BIT(1)
> of watchdog control register is wakeup interrupt enable bit and
> not related to bark interrupt at all, BIT(0) is used for that.
> So remove incorrect usage of this bit when supporting bark irq for
> pre-timeout notification. Currently with this bit set and bark
> interrupt specified, pre-timeout notification and/or watchdog
> reset/bite does not occur.

It looks like the QCOM_WDT_ENABLE_IRQ bit is to catch a problem where a
pending irq is unmasked but the watchdog irq isn't handled in time? So
some sort of irq storm?

> 
> Fixes: 36375491a439 ("watchdog: qcom: support pre-timeout when the bark irq is available")
> Cc: stable@vger.kernel.org
> Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
> ---

Reviewed-by: Stephen Boyd <swboyd@chromium.org>

Re: [PATCH] watchdog: qcom: Remove incorrect usage of QCOM_WDT_ENABLE_IRQ

[Sai Prakash Ranjan]

On 2021-01-28 07:03, Stephen Boyd wrote:
> Quoting Sai Prakash Ranjan (2021-01-26 07:02:41)
>> As per register documentation, QCOM_WDT_ENABLE_IRQ which is BIT(1)
>> of watchdog control register is wakeup interrupt enable bit and
>> not related to bark interrupt at all, BIT(0) is used for that.
>> So remove incorrect usage of this bit when supporting bark irq for
>> pre-timeout notification. Currently with this bit set and bark
>> interrupt specified, pre-timeout notification and/or watchdog
>> reset/bite does not occur.
> 
> It looks like the QCOM_WDT_ENABLE_IRQ bit is to catch a problem where a
> pending irq is unmasked but the watchdog irq isn't handled in time? So
> some sort of irq storm?
> 

In sleep mode, this bit is used to enable unmasked irq to wakeup
watchdog timer. The watchdog counter can be brought out of
reset either by writing 1 to WDOG_RESET or setting this BIT(1) to 1.

>> 
>> Fixes: 36375491a439 ("watchdog: qcom: support pre-timeout when the 
>> bark irq is available")
>> Cc: stable@vger.kernel.org
>> Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
>> ---
> 
> Reviewed-by: Stephen Boyd <swboyd@chromium.org>
> 

Thanks,
Sai

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member
of Code Aurora Forum, hosted by The Linux Foundation

Re: [PATCH] watchdog: qcom: Remove incorrect usage of QCOM_WDT_ENABLE_IRQ

[Jorge Ramirez-Ortiz, Foundries]

On 26/01/21, Sai Prakash Ranjan wrote:
> As per register documentation, QCOM_WDT_ENABLE_IRQ which is BIT(1)
> of watchdog control register is wakeup interrupt enable bit and
> not related to bark interrupt at all, BIT(0) is used for that.
> So remove incorrect usage of this bit when supporting bark irq for
> pre-timeout notification. Currently with this bit set and bark
> interrupt specified, pre-timeout notification and/or watchdog
> reset/bite does not occur.
> 
> Fixes: 36375491a439 ("watchdog: qcom: support pre-timeout when the bark irq is available")
> Cc: stable@vger.kernel.org
> Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
> ---
> 
> Reading the conversations from when qcom pre-timeout support was
> added [1], Bjorn already had mentioned it was not right to touch this
> bit, not sure which SoC the pre-timeout was tested on at that time,
> but I have tested this on SDM845, SM8150, SC7180 and watchdog bark
> and bite does not occur with enabling this bit with the bark irq
> specified in DT.

this was tested on QCS404. have you validated there? unfortunately I
no longer have access to that hardware or the documentation


> 
> [1] https://lore.kernel.org/linux-watchdog/20190906174009.GC11938@tuxbook-pro/
> 
> ---
>  drivers/watchdog/qcom-wdt.c | 13 +------------
>  1 file changed, 1 insertion(+), 12 deletions(-)
> 
> diff --git a/drivers/watchdog/qcom-wdt.c b/drivers/watchdog/qcom-wdt.c
> index 7cf0f2ec649b..e38a87ffe5f5 100644
> --- a/drivers/watchdog/qcom-wdt.c
> +++ b/drivers/watchdog/qcom-wdt.c
> @@ -22,7 +22,6 @@ enum wdt_reg {
>  };
>  
>  #define QCOM_WDT_ENABLE		BIT(0)
> -#define QCOM_WDT_ENABLE_IRQ	BIT(1)
>  
>  static const u32 reg_offset_data_apcs_tmr[] = {
>  	[WDT_RST] = 0x38,
> @@ -63,16 +62,6 @@ struct qcom_wdt *to_qcom_wdt(struct watchdog_device *wdd)
>  	return container_of(wdd, struct qcom_wdt, wdd);
>  }
>  
> -static inline int qcom_get_enable(struct watchdog_device *wdd)
> -{
> -	int enable = QCOM_WDT_ENABLE;
> -
> -	if (wdd->pretimeout)
> -		enable |= QCOM_WDT_ENABLE_IRQ;
> -
> -	return enable;
> -}
> -
>  static irqreturn_t qcom_wdt_isr(int irq, void *arg)
>  {
>  	struct watchdog_device *wdd = arg;
> @@ -91,7 +80,7 @@ static int qcom_wdt_start(struct watchdog_device *wdd)
>  	writel(1, wdt_addr(wdt, WDT_RST));
>  	writel(bark * wdt->rate, wdt_addr(wdt, WDT_BARK_TIME));
>  	writel(wdd->timeout * wdt->rate, wdt_addr(wdt, WDT_BITE_TIME));
> -	writel(qcom_get_enable(wdd), wdt_addr(wdt, WDT_EN));
> +	writel(QCOM_WDT_ENABLE, wdt_addr(wdt, WDT_EN));
>  	return 0;
>  }
>  
> -- 
> QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
> of Code Aurora Forum, hosted by The Linux Foundation
> 

Re: [PATCH] watchdog: qcom: Remove incorrect usage of QCOM_WDT_ENABLE_IRQ

[Sai Prakash Ranjan]

On 2021-01-28 13:49, Jorge Ramirez-Ortiz, Foundries wrote:
> On 26/01/21, Sai Prakash Ranjan wrote:
>> As per register documentation, QCOM_WDT_ENABLE_IRQ which is BIT(1)
>> of watchdog control register is wakeup interrupt enable bit and
>> not related to bark interrupt at all, BIT(0) is used for that.
>> So remove incorrect usage of this bit when supporting bark irq for
>> pre-timeout notification. Currently with this bit set and bark
>> interrupt specified, pre-timeout notification and/or watchdog
>> reset/bite does not occur.
>> 
>> Fixes: 36375491a439 ("watchdog: qcom: support pre-timeout when the 
>> bark irq is available")
>> Cc: stable@vger.kernel.org
>> Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
>> ---
>> 
>> Reading the conversations from when qcom pre-timeout support was
>> added [1], Bjorn already had mentioned it was not right to touch this
>> bit, not sure which SoC the pre-timeout was tested on at that time,
>> but I have tested this on SDM845, SM8150, SC7180 and watchdog bark
>> and bite does not occur with enabling this bit with the bark irq
>> specified in DT.
> 
> this was tested on QCS404. have you validated there? unfortunately I
> no longer have access to that hardware or the documentation
> 

I didn't validate on qcs404 yet since I didn't have access to it.
But now that you mention it, let me arrange for a setup and test it
there as well. Note: I did not see bark irq entry in upstream qcs404
dtsi, so you must have had some local change when you tested?

Thanks,
Sai

-- 
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a 
member
of Code Aurora Forum, hosted by The Linux Foundation

Re: [PATCH] watchdog: qcom: Remove incorrect usage of QCOM_WDT_ENABLE_IRQ

[Sai Prakash Ranjan]

On 2021-01-31 22:33, Jorge Ramirez-Ortiz, Foundries wrote:
> On 28/01/21, Sai Prakash Ranjan wrote:
>> On 2021-01-28 13:49, Jorge Ramirez-Ortiz, Foundries wrote:
>> > On 26/01/21, Sai Prakash Ranjan wrote:
>> > > As per register documentation, QCOM_WDT_ENABLE_IRQ which is BIT(1)
>> > > of watchdog control register is wakeup interrupt enable bit and
>> > > not related to bark interrupt at all, BIT(0) is used for that.
>> > > So remove incorrect usage of this bit when supporting bark irq for
>> > > pre-timeout notification. Currently with this bit set and bark
>> > > interrupt specified, pre-timeout notification and/or watchdog
>> > > reset/bite does not occur.
>> > >
>> > > Fixes: 36375491a439 ("watchdog: qcom: support pre-timeout when the
>> > > bark irq is available")
>> > > Cc: stable@vger.kernel.org
>> > > Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
>> > > ---
>> > >
>> > > Reading the conversations from when qcom pre-timeout support was
>> > > added [1], Bjorn already had mentioned it was not right to touch this
>> > > bit, not sure which SoC the pre-timeout was tested on at that time,
>> > > but I have tested this on SDM845, SM8150, SC7180 and watchdog bark
>> > > and bite does not occur with enabling this bit with the bark irq
>> > > specified in DT.
>> >
>> > this was tested on QCS404. have you validated there? unfortunately I
>> > no longer have access to that hardware or the documentation
>> >
>> 
>> I didn't validate on qcs404 yet since I didn't have access to it.
>> But now that you mention it, let me arrange for a setup and test it
>> there as well. Note: I did not see bark irq entry in upstream qcs404
>> dtsi, so you must have had some local change when you tested?
> 
> TBH I dont quite remember. I suppose that if those with access to the
> documents and hardware are OK with this change then it shouldnt cause
> regressions (I just cant check from my end)
> 

No worries, I got the documentation access now and it is the same as
other SoCs which I have tested above, meaning the BIT(1) is not related
to bark irq. I am arranging a setup as well now, it took some time as
I don't work on QCS* chipsets but I can confirm by this week.

Thanks,
Sai

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member
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