Linux-Watchdog Archive on lore.kernel.org
 help / color / Atom feed
* [PATCH] watchdog: mtk: support pre-timeout when the bark irq is available
@ 2021-04-09  9:55 Wang Qing
  2021-04-09 12:56 ` Guenter Roeck
  0 siblings, 1 reply; 7+ messages in thread
From: Wang Qing @ 2021-04-09  9:55 UTC (permalink / raw)
  To: Wim Van Sebroeck, Guenter Roeck, Matthias Brugger,
	linux-watchdog, linux-arm-kernel, linux-mediatek, linux-kernel
  Cc: Wang Qing

Use the bark interrupt as the pretimeout notifier if available.

By default, the pretimeout notification shall occur one second earlier
than the timeout.

Signed-off-by: Wang Qing <wangqing@vivo.com>
---
 drivers/watchdog/mtk_wdt.c | 47 +++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 44 insertions(+), 3 deletions(-)

diff --git a/drivers/watchdog/mtk_wdt.c b/drivers/watchdog/mtk_wdt.c
index 97ca993..8b919cc
--- a/drivers/watchdog/mtk_wdt.c
+++ b/drivers/watchdog/mtk_wdt.c
@@ -25,6 +25,7 @@
 #include <linux/reset-controller.h>
 #include <linux/types.h>
 #include <linux/watchdog.h>
+#include <linux/interrupt.h>
 
 #define WDT_MAX_TIMEOUT		31
 #define WDT_MIN_TIMEOUT		1
@@ -234,18 +235,35 @@ static int mtk_wdt_start(struct watchdog_device *wdt_dev)
 	void __iomem *wdt_base = mtk_wdt->wdt_base;
 	int ret;
 
-	ret = mtk_wdt_set_timeout(wdt_dev, wdt_dev->timeout);
+	ret = mtk_wdt_set_timeout(wdt_dev, wdt_dev->timeout - wdt_dev->pretimeout);
 	if (ret < 0)
 		return ret;
 
 	reg = ioread32(wdt_base + WDT_MODE);
 	reg &= ~(WDT_MODE_IRQ_EN | WDT_MODE_DUAL_EN);
+	if (wdt_dev->pretimeout)
+		reg |= WDT_MODE_IRQ_EN;
 	reg |= (WDT_MODE_EN | WDT_MODE_KEY);
 	iowrite32(reg, wdt_base + WDT_MODE);
 
 	return 0;
 }
 
+static int mtk_wdt_set_pretimeout(struct watchdog_device *wdd,
+				   unsigned int timeout)
+{
+	wdd->pretimeout = timeout;
+	return mtk_wdt_start(wdd);
+}
+
+static irqreturn_t mtk_wdt_isr(int irq, void *arg)
+{
+	struct watchdog_device *wdd = arg;
+	watchdog_notify_pretimeout(wdd);
+
+	return IRQ_HANDLED;
+}
+
 static const struct watchdog_info mtk_wdt_info = {
 	.identity	= DRV_NAME,
 	.options	= WDIOF_SETTIMEOUT |
@@ -253,12 +271,21 @@ static const struct watchdog_info mtk_wdt_info = {
 			  WDIOF_MAGICCLOSE,
 };
 
+static const struct watchdog_info mtk_wdt_pt_info = {
+	.identity	= DRV_NAME,
+	.options	= WDIOF_SETTIMEOUT |
+			  WDIOF_PRETIMEOUT |
+			  WDIOF_KEEPALIVEPING |
+			  WDIOF_MAGICCLOSE,
+};
+
 static const struct watchdog_ops mtk_wdt_ops = {
 	.owner		= THIS_MODULE,
 	.start		= mtk_wdt_start,
 	.stop		= mtk_wdt_stop,
 	.ping		= mtk_wdt_ping,
 	.set_timeout	= mtk_wdt_set_timeout,
+	.set_pretimeout	= mtk_wdt_set_pretimeout,
 	.restart	= mtk_wdt_restart,
 };
 
@@ -267,7 +294,7 @@ static int mtk_wdt_probe(struct platform_device *pdev)
 	struct device *dev = &pdev->dev;
 	struct mtk_wdt_dev *mtk_wdt;
 	const struct mtk_wdt_data *wdt_data;
-	int err;
+	int err,irq;
 
 	mtk_wdt = devm_kzalloc(dev, sizeof(*mtk_wdt), GFP_KERNEL);
 	if (!mtk_wdt)
@@ -279,7 +306,21 @@ static int mtk_wdt_probe(struct platform_device *pdev)
 	if (IS_ERR(mtk_wdt->wdt_base))
 		return PTR_ERR(mtk_wdt->wdt_base);
 
-	mtk_wdt->wdt_dev.info = &mtk_wdt_info;
+	irq = platform_get_irq(pdev, 0);
+	if (irq > 0) {
+		err = devm_request_irq(&pdev->dev, irq, mtk_wdt_isr, 0, "wdt_bark", &mtk_wdt->wdt_dev);
+		if (err)
+			return err;
+
+		mtk_wdt->wdt_dev.info = &mtk_wdt_pt_info;
+		mtk_wdt->wdt_dev.pretimeout = 1;
+	} else {
+		if (irq == -EPROBE_DEFER)
+			return -EPROBE_DEFER;
+
+		mtk_wdt->wdt_dev.info = &mtk_wdt_info;
+	}
+
 	mtk_wdt->wdt_dev.ops = &mtk_wdt_ops;
 	mtk_wdt->wdt_dev.timeout = WDT_MAX_TIMEOUT;
 	mtk_wdt->wdt_dev.max_hw_heartbeat_ms = WDT_MAX_TIMEOUT * 1000;
-- 
2.7.4


^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH] watchdog: mtk: support pre-timeout when the bark irq is available
  2021-04-09  9:55 [PATCH] watchdog: mtk: support pre-timeout when the bark irq is available Wang Qing
@ 2021-04-09 12:56 ` Guenter Roeck
  2021-04-10  2:42   ` 王擎
  0 siblings, 1 reply; 7+ messages in thread
From: Guenter Roeck @ 2021-04-09 12:56 UTC (permalink / raw)
  To: Wang Qing, Wim Van Sebroeck, Matthias Brugger, linux-watchdog,
	linux-arm-kernel, linux-mediatek, linux-kernel

On 4/9/21 2:55 AM, Wang Qing wrote:
> Use the bark interrupt as the pretimeout notifier if available.
> 
> By default, the pretimeout notification shall occur one second earlier
> than the timeout.
> 
> Signed-off-by: Wang Qing <wangqing@vivo.com>
> ---
>  drivers/watchdog/mtk_wdt.c | 47 +++++++++++++++++++++++++++++++++++++++++++---
>  1 file changed, 44 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/watchdog/mtk_wdt.c b/drivers/watchdog/mtk_wdt.c
> index 97ca993..8b919cc
> --- a/drivers/watchdog/mtk_wdt.c
> +++ b/drivers/watchdog/mtk_wdt.c
> @@ -25,6 +25,7 @@
>  #include <linux/reset-controller.h>
>  #include <linux/types.h>
>  #include <linux/watchdog.h>
> +#include <linux/interrupt.h>
>  
>  #define WDT_MAX_TIMEOUT		31
>  #define WDT_MIN_TIMEOUT		1
> @@ -234,18 +235,35 @@ static int mtk_wdt_start(struct watchdog_device *wdt_dev)
>  	void __iomem *wdt_base = mtk_wdt->wdt_base;
>  	int ret;
>  
> -	ret = mtk_wdt_set_timeout(wdt_dev, wdt_dev->timeout);
> +	ret = mtk_wdt_set_timeout(wdt_dev, wdt_dev->timeout - wdt_dev->pretimeout);

That looks suspiciously like the real watchdog won't happen at all.
What will happen if the pretimeout governor is set to none ?

Guenter

>  	if (ret < 0)
>  		return ret;
>  
>  	reg = ioread32(wdt_base + WDT_MODE);
>  	reg &= ~(WDT_MODE_IRQ_EN | WDT_MODE_DUAL_EN);
> +	if (wdt_dev->pretimeout)
> +		reg |= WDT_MODE_IRQ_EN;
>  	reg |= (WDT_MODE_EN | WDT_MODE_KEY);
>  	iowrite32(reg, wdt_base + WDT_MODE);
>  
>  	return 0;
>  }
>  
> +static int mtk_wdt_set_pretimeout(struct watchdog_device *wdd,
> +				   unsigned int timeout)
> +{
> +	wdd->pretimeout = timeout;
> +	return mtk_wdt_start(wdd);
> +}
> +
> +static irqreturn_t mtk_wdt_isr(int irq, void *arg)
> +{
> +	struct watchdog_device *wdd = arg;
> +	watchdog_notify_pretimeout(wdd);
> +
> +	return IRQ_HANDLED;
> +}
> +
>  static const struct watchdog_info mtk_wdt_info = {
>  	.identity	= DRV_NAME,
>  	.options	= WDIOF_SETTIMEOUT |
> @@ -253,12 +271,21 @@ static const struct watchdog_info mtk_wdt_info = {
>  			  WDIOF_MAGICCLOSE,
>  };
>  
> +static const struct watchdog_info mtk_wdt_pt_info = {
> +	.identity	= DRV_NAME,
> +	.options	= WDIOF_SETTIMEOUT |
> +			  WDIOF_PRETIMEOUT |
> +			  WDIOF_KEEPALIVEPING |
> +			  WDIOF_MAGICCLOSE,
> +};
> +
>  static const struct watchdog_ops mtk_wdt_ops = {
>  	.owner		= THIS_MODULE,
>  	.start		= mtk_wdt_start,
>  	.stop		= mtk_wdt_stop,
>  	.ping		= mtk_wdt_ping,
>  	.set_timeout	= mtk_wdt_set_timeout,
> +	.set_pretimeout	= mtk_wdt_set_pretimeout,
>  	.restart	= mtk_wdt_restart,
>  };
>  
> @@ -267,7 +294,7 @@ static int mtk_wdt_probe(struct platform_device *pdev)
>  	struct device *dev = &pdev->dev;
>  	struct mtk_wdt_dev *mtk_wdt;
>  	const struct mtk_wdt_data *wdt_data;
> -	int err;
> +	int err,irq;
>  
>  	mtk_wdt = devm_kzalloc(dev, sizeof(*mtk_wdt), GFP_KERNEL);
>  	if (!mtk_wdt)
> @@ -279,7 +306,21 @@ static int mtk_wdt_probe(struct platform_device *pdev)
>  	if (IS_ERR(mtk_wdt->wdt_base))
>  		return PTR_ERR(mtk_wdt->wdt_base);
>  
> -	mtk_wdt->wdt_dev.info = &mtk_wdt_info;
> +	irq = platform_get_irq(pdev, 0);
> +	if (irq > 0) {
> +		err = devm_request_irq(&pdev->dev, irq, mtk_wdt_isr, 0, "wdt_bark", &mtk_wdt->wdt_dev);
> +		if (err)
> +			return err;
> +
> +		mtk_wdt->wdt_dev.info = &mtk_wdt_pt_info;
> +		mtk_wdt->wdt_dev.pretimeout = 1;
> +	} else {
> +		if (irq == -EPROBE_DEFER)
> +			return -EPROBE_DEFER;
> +
> +		mtk_wdt->wdt_dev.info = &mtk_wdt_info;
> +	}
> +
>  	mtk_wdt->wdt_dev.ops = &mtk_wdt_ops;
>  	mtk_wdt->wdt_dev.timeout = WDT_MAX_TIMEOUT;
>  	mtk_wdt->wdt_dev.max_hw_heartbeat_ms = WDT_MAX_TIMEOUT * 1000;
> 


^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re:Re: [PATCH] watchdog: mtk: support pre-timeout when the bark irq is available
  2021-04-09 12:56 ` Guenter Roeck
@ 2021-04-10  2:42   ` 王擎
  2021-04-10  2:56     ` Guenter Roeck
  0 siblings, 1 reply; 7+ messages in thread
From: 王擎 @ 2021-04-10  2:42 UTC (permalink / raw)
  To: Guenter Roeck
  Cc: Wim Van Sebroeck, Matthias Brugger, linux-watchdog,
	linux-arm-kernel, linux-mediatek, linux-kernel


>On 4/9/21 2:55 AM, Wang Qing wrote:
>> Use the bark interrupt as the pretimeout notifier if available.
>> 
>> By default, the pretimeout notification shall occur one second earlier
>> than the timeout.
>> 
>> Signed-off-by: Wang Qing <wangqing@vivo.com>
>> ---
>>  drivers/watchdog/mtk_wdt.c | 47 +++++++++++++++++++++++++++++++++++++++++++---
>>  1 file changed, 44 insertions(+), 3 deletions(-)
>> 
>> diff --git a/drivers/watchdog/mtk_wdt.c b/drivers/watchdog/mtk_wdt.c
>> index 97ca993..8b919cc
>> --- a/drivers/watchdog/mtk_wdt.c
>> +++ b/drivers/watchdog/mtk_wdt.c
>> @@ -25,6 +25,7 @@
>>  #include <linux/reset-controller.h>
>>  #include <linux/types.h>
>>  #include <linux/watchdog.h>
>> +#include <linux/interrupt.h>
>>  
>>  #define WDT_MAX_TIMEOUT		31
>>  #define WDT_MIN_TIMEOUT		1
>> @@ -234,18 +235,35 @@ static int mtk_wdt_start(struct watchdog_device *wdt_dev)
>>  	void __iomem *wdt_base = mtk_wdt->wdt_base;
>>  	int ret;
>>  
>> -	ret = mtk_wdt_set_timeout(wdt_dev, wdt_dev->timeout);
>> +	ret = mtk_wdt_set_timeout(wdt_dev, wdt_dev->timeout - wdt_dev->pretimeout);
>
>That looks suspiciously like the real watchdog won't happen at all.
>What will happen if the pretimeout governor is set to none ?
>
>Guenter
>
The pretimeout governor is panic by default. If pretimeout is enabled and the governor is
set to none, it means the timeout behavior does not need to be processed, only printing.

Thanks.

Qing Wang.



^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH] watchdog: mtk: support pre-timeout when the bark irq is available
  2021-04-10  2:42   ` 王擎
@ 2021-04-10  2:56     ` Guenter Roeck
  2021-04-10  3:11       ` 王擎
  0 siblings, 1 reply; 7+ messages in thread
From: Guenter Roeck @ 2021-04-10  2:56 UTC (permalink / raw)
  To: 王擎
  Cc: Wim Van Sebroeck, Matthias Brugger, linux-watchdog,
	linux-arm-kernel, linux-mediatek, linux-kernel

On 4/9/21 7:42 PM, 王擎 wrote:
> 
>> On 4/9/21 2:55 AM, Wang Qing wrote:
>>> Use the bark interrupt as the pretimeout notifier if available.
>>>
>>> By default, the pretimeout notification shall occur one second earlier
>>> than the timeout.
>>>
>>> Signed-off-by: Wang Qing <wangqing@vivo.com>
>>> ---
>>>  drivers/watchdog/mtk_wdt.c | 47 +++++++++++++++++++++++++++++++++++++++++++---
>>>  1 file changed, 44 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/watchdog/mtk_wdt.c b/drivers/watchdog/mtk_wdt.c
>>> index 97ca993..8b919cc
>>> --- a/drivers/watchdog/mtk_wdt.c
>>> +++ b/drivers/watchdog/mtk_wdt.c
>>> @@ -25,6 +25,7 @@
>>>  #include <linux/reset-controller.h>
>>>  #include <linux/types.h>
>>>  #include <linux/watchdog.h>
>>> +#include <linux/interrupt.h>
>>>  
>>>  #define WDT_MAX_TIMEOUT		31
>>>  #define WDT_MIN_TIMEOUT		1
>>> @@ -234,18 +235,35 @@ static int mtk_wdt_start(struct watchdog_device *wdt_dev)
>>>  	void __iomem *wdt_base = mtk_wdt->wdt_base;
>>>  	int ret;
>>>  
>>> -	ret = mtk_wdt_set_timeout(wdt_dev, wdt_dev->timeout);
>>> +	ret = mtk_wdt_set_timeout(wdt_dev, wdt_dev->timeout - wdt_dev->pretimeout);
>>
>> That looks suspiciously like the real watchdog won't happen at all.
>> What will happen if the pretimeout governor is set to none ?
>>
>> Guenter
>>
> The pretimeout governor is panic by default. If pretimeout is enabled and the governor is
> set to none, it means the timeout behavior does not need to be processed, only printing.
> 

That was not my question. My question was if the real timeout happens in that case.

Guenter


^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re:Re: [PATCH] watchdog: mtk: support pre-timeout when the bark irq is available
  2021-04-10  2:56     ` Guenter Roeck
@ 2021-04-10  3:11       ` 王擎
  2021-04-10  4:35         ` Guenter Roeck
  0 siblings, 1 reply; 7+ messages in thread
From: 王擎 @ 2021-04-10  3:11 UTC (permalink / raw)
  To: Guenter Roeck
  Cc: Wim Van Sebroeck, Matthias Brugger, linux-watchdog,
	linux-arm-kernel, linux-mediatek, linux-kernel


>On 4/9/21 7:42 PM, 王擎 wrote:
>> 
>>> On 4/9/21 2:55 AM, Wang Qing wrote:
>>>> Use the bark interrupt as the pretimeout notifier if available.
>>>>
>>>> By default, the pretimeout notification shall occur one second earlier
>>>> than the timeout.
>>>>
>>>> Signed-off-by: Wang Qing <wangqing@vivo.com>
>>>> ---
>>>>  drivers/watchdog/mtk_wdt.c | 47 +++++++++++++++++++++++++++++++++++++++++++---
>>>>  1 file changed, 44 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/drivers/watchdog/mtk_wdt.c b/drivers/watchdog/mtk_wdt.c
>>>> index 97ca993..8b919cc
>>>> --- a/drivers/watchdog/mtk_wdt.c
>>>> +++ b/drivers/watchdog/mtk_wdt.c
>>>> @@ -25,6 +25,7 @@
>>>>  #include <linux/reset-controller.h>
>>>>  #include <linux/types.h>
>>>>  #include <linux/watchdog.h>
>>>> +#include <linux/interrupt.h>
>>>>  
>>>>  #define WDT_MAX_TIMEOUT		31
>>>>  #define WDT_MIN_TIMEOUT		1
>>>> @@ -234,18 +235,35 @@ static int mtk_wdt_start(struct watchdog_device *wdt_dev)
>>>>  	void __iomem *wdt_base = mtk_wdt->wdt_base;
>>>>  	int ret;
>>>>  
>>>> -	ret = mtk_wdt_set_timeout(wdt_dev, wdt_dev->timeout);
>>>> +	ret = mtk_wdt_set_timeout(wdt_dev, wdt_dev->timeout - wdt_dev->pretimeout);
>>>
>>> That looks suspiciously like the real watchdog won't happen at all.
>>> What will happen if the pretimeout governor is set to none ?
>>>
>>> Guenter
>>>
>> The pretimeout governor is panic by default. If pretimeout is enabled and the governor is
>> set to none, it means the timeout behavior does not need to be processed, only printing.
>> 
>
>That was not my question. My question was if the real timeout happens in that case.
>
>Guenter
>
Yes, the real timeout will happen. After WDT timeout, IRQ is sent out instead of 
reset signal first. In order to ensure that CPU does not get stuck after IRQ is sent out, 
WDT will time again and send reset signal to reset.

Thanks.
Qing Wang.


^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH] watchdog: mtk: support pre-timeout when the bark irq is available
  2021-04-10  3:11       ` 王擎
@ 2021-04-10  4:35         ` Guenter Roeck
  2021-04-10 12:19           ` 王擎
  0 siblings, 1 reply; 7+ messages in thread
From: Guenter Roeck @ 2021-04-10  4:35 UTC (permalink / raw)
  To: 王擎
  Cc: Wim Van Sebroeck, Matthias Brugger, linux-watchdog,
	linux-arm-kernel, linux-mediatek, linux-kernel

On 4/9/21 8:11 PM, 王擎 wrote:
> 
>> On 4/9/21 7:42 PM, 王擎 wrote:
>>>
>>>> On 4/9/21 2:55 AM, Wang Qing wrote:
>>>>> Use the bark interrupt as the pretimeout notifier if available.
>>>>>
>>>>> By default, the pretimeout notification shall occur one second earlier
>>>>> than the timeout.
>>>>>
>>>>> Signed-off-by: Wang Qing <wangqing@vivo.com>
>>>>> ---
>>>>>  drivers/watchdog/mtk_wdt.c | 47 +++++++++++++++++++++++++++++++++++++++++++---
>>>>>  1 file changed, 44 insertions(+), 3 deletions(-)
>>>>>
>>>>> diff --git a/drivers/watchdog/mtk_wdt.c b/drivers/watchdog/mtk_wdt.c
>>>>> index 97ca993..8b919cc
>>>>> --- a/drivers/watchdog/mtk_wdt.c
>>>>> +++ b/drivers/watchdog/mtk_wdt.c
>>>>> @@ -25,6 +25,7 @@
>>>>>  #include <linux/reset-controller.h>
>>>>>  #include <linux/types.h>
>>>>>  #include <linux/watchdog.h>
>>>>> +#include <linux/interrupt.h>
>>>>>  
>>>>>  #define WDT_MAX_TIMEOUT		31
>>>>>  #define WDT_MIN_TIMEOUT		1
>>>>> @@ -234,18 +235,35 @@ static int mtk_wdt_start(struct watchdog_device *wdt_dev)
>>>>>  	void __iomem *wdt_base = mtk_wdt->wdt_base;
>>>>>  	int ret;
>>>>>  
>>>>> -	ret = mtk_wdt_set_timeout(wdt_dev, wdt_dev->timeout);
>>>>> +	ret = mtk_wdt_set_timeout(wdt_dev, wdt_dev->timeout - wdt_dev->pretimeout);
>>>>
>>>> That looks suspiciously like the real watchdog won't happen at all.
>>>> What will happen if the pretimeout governor is set to none ?
>>>>
>>>> Guenter
>>>>
>>> The pretimeout governor is panic by default. If pretimeout is enabled and the governor is
>>> set to none, it means the timeout behavior does not need to be processed, only printing.
>>>
>>
>> That was not my question. My question was if the real timeout happens in that case.
>>
>> Guenter
>>
> Yes, the real timeout will happen. After WDT timeout, IRQ is sent out instead of 
> reset signal first. In order to ensure that CPU does not get stuck after IRQ is sent out, 
> WDT will time again and send reset signal to reset.
> 

When will that be, or in other words how does the chip know when to time out ?
After all, only a single timeout value is written into the chip. I don't see how
it would know to reset the chip after wdt_dev->timeout.

Guenter



^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re:Re: [PATCH] watchdog: mtk: support pre-timeout when the bark irq is available
  2021-04-10  4:35         ` Guenter Roeck
@ 2021-04-10 12:19           ` 王擎
  0 siblings, 0 replies; 7+ messages in thread
From: 王擎 @ 2021-04-10 12:19 UTC (permalink / raw)
  To: Guenter Roeck
  Cc: Wim Van Sebroeck, Matthias Brugger, linux-watchdog,
	linux-arm-kernel, linux-mediatek, linux-kernel


>On 4/9/21 8:11 PM, 王擎 wrote:
>> 
>>> On 4/9/21 7:42 PM, 王擎 wrote:
>>>>
>>>>> On 4/9/21 2:55 AM, Wang Qing wrote:
>>>>>> Use the bark interrupt as the pretimeout notifier if available.
>>>>>>
>>>>>> By default, the pretimeout notification shall occur one second earlier
>>>>>> than the timeout.
>>>>>>
>>>>>> Signed-off-by: Wang Qing <wangqing@vivo.com>
>>>>>> ---
>>>>>>  drivers/watchdog/mtk_wdt.c | 47 +++++++++++++++++++++++++++++++++++++++++++---
>>>>>>  1 file changed, 44 insertions(+), 3 deletions(-)
>>>>>>
>>>>>> diff --git a/drivers/watchdog/mtk_wdt.c b/drivers/watchdog/mtk_wdt.c
>>>>>> index 97ca993..8b919cc
>>>>>> --- a/drivers/watchdog/mtk_wdt.c
>>>>>> +++ b/drivers/watchdog/mtk_wdt.c
>>>>>> @@ -25,6 +25,7 @@
>>>>>>  #include <linux/reset-controller.h>
>>>>>>  #include <linux/types.h>
>>>>>>  #include <linux/watchdog.h>
>>>>>> +#include <linux/interrupt.h>
>>>>>>  
>>>>>>  #define WDT_MAX_TIMEOUT		31
>>>>>>  #define WDT_MIN_TIMEOUT		1
>>>>>> @@ -234,18 +235,35 @@ static int mtk_wdt_start(struct watchdog_device *wdt_dev)
>>>>>>  	void __iomem *wdt_base = mtk_wdt->wdt_base;
>>>>>>  	int ret;
>>>>>>  
>>>>>> -	ret = mtk_wdt_set_timeout(wdt_dev, wdt_dev->timeout);
>>>>>> +	ret = mtk_wdt_set_timeout(wdt_dev, wdt_dev->timeout - wdt_dev->pretimeout);
>>>>>
>>>>> That looks suspiciously like the real watchdog won't happen at all.
>>>>> What will happen if the pretimeout governor is set to none ?
>>>>>
>>>>> Guenter
>>>>>
>>>> The pretimeout governor is panic by default. If pretimeout is enabled and the governor is
>>>> set to none, it means the timeout behavior does not need to be processed, only printing.
>>>>
>>>
>>> That was not my question. My question was if the real timeout happens in that case.
>>>
>>> Guenter
>>>
>> Yes, the real timeout will happen. After WDT timeout, IRQ is sent out instead of 
>> reset signal first. In order to ensure that CPU does not get stuck after IRQ is sent out, 
>> WDT will time again and send reset signal to reset.
>> 
>
>When will that be, or in other words how does the chip know when to time out ?
>After all, only a single timeout value is written into the chip. I don't see how
>it would know to reset the chip after wdt_dev->timeout.
>
>Guenter
>
>
Sorry I made a mistake, the IRQ is sent out first, then time again and reset only when 
WDT_MODE_IRQ_EN|WDT_MODE_DUAL_EN is enabled. WDT_MODE_DUAL_EN mode
is a special mode, depending on the specific chip design.

If WDT_MODE_IRQ_EN|~WDT_MODE_DUAL_EN as described in my patch, it just sent
out IRQ instead of reset signal, the real timeout will not happen if the pretimeout 
governor is set to none.

Also, ~(WDT_MODE_IRQ_EN | WDT_MODE_DUAL_EN) means send reset signal directly.
It does not support pretimeout processing.

Thanks
Qing Wang


^ permalink raw reply	[flat|nested] 7+ messages in thread

end of thread, back to index

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-04-09  9:55 [PATCH] watchdog: mtk: support pre-timeout when the bark irq is available Wang Qing
2021-04-09 12:56 ` Guenter Roeck
2021-04-10  2:42   ` 王擎
2021-04-10  2:56     ` Guenter Roeck
2021-04-10  3:11       ` 王擎
2021-04-10  4:35         ` Guenter Roeck
2021-04-10 12:19           ` 王擎

Linux-Watchdog Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-watchdog/0 linux-watchdog/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-watchdog linux-watchdog/ https://lore.kernel.org/linux-watchdog \
		linux-watchdog@vger.kernel.org
	public-inbox-index linux-watchdog

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-watchdog


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git