Message-ID: <20210423141048.GA135134@roeck-us.net>
Date:   Fri, 23 Apr 2021 07:10:48 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     王擎 <wangqing@...o.com>
Cc:     Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Rob Herring <robh+dt@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        linux-watchdog@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: Re: [PATCH V7 1/2] watchdog: mtk: support pre-timeout when the
 bark irq is available

On Fri, Apr 23, 2021 at 03:12:24PM +0800, 王擎 wrote:
> 
> >On 4/22/21 8:48 PM, 王擎 wrote:
> >> 
> >>> On 4/22/21 7:53 PM, Wang Qing wrote:
> >>>> Use the bark interrupt as the pretimeout notifier if available.
> >>>>
> >>>> When the watchdog timer expires in dual mode, an interrupt will be
> >>>> triggered first, then the timing restarts. The reset signal will be
> >>>> initiated when the timer expires again.
> >>>>
> >>>> The pretimeout notification shall occur at timeout-sec/2.
> >>>>
> >>>> V2:
> >>>> - panic() by default if WATCHDOG_PRETIMEOUT_GOV is not enabled.
> >>>>
> >>>> V3:
> >>>> - Modify the pretimeout behavior, manually reset after the pretimeout
> >>>> - is processed and wait until timeout.
> >>>>
> >>>> V4:
> >>>> - Remove pretimeout related processing. 
> >>>> - Add dual mode control separately.
> >>>>
> >>>> V5:
> >>>> - Fix some formatting and printing problems.
> >>>>
> >>>> V6:
> >>>> - Realize pretimeout processing through dualmode.
> >>>>
> >>>> V7:
> >>>> - Add set_pretimeout().
> >>>>
> >>>> Signed-off-by: Wang Qing <wangqing@...o.com>
> >>>> ---
> >>>>  drivers/watchdog/mtk_wdt.c | 76 +++++++++++++++++++++++++++++++++++++++++++---
> >>>>  1 file changed, 71 insertions(+), 5 deletions(-)
> >>>>
> >>>> diff --git a/drivers/watchdog/mtk_wdt.c b/drivers/watchdog/mtk_wdt.c
> >>>> index 97ca993..ab3ac5d
> >>>> --- 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
> >>>> @@ -184,15 +185,23 @@ static int mtk_wdt_set_timeout(struct watchdog_device *wdt_dev,
> >>>>  {
> >>>>  	struct mtk_wdt_dev *mtk_wdt = watchdog_get_drvdata(wdt_dev);
> >>>>  	void __iomem *wdt_base = mtk_wdt->wdt_base;
> >>>> +	unsigned int timeout_interval = timeout;
> >>>>  	u32 reg;
> >>>>  
> >>>>  	wdt_dev->timeout = timeout;
> >>>> -
> >>>> +	/*
> >>>> +	 * In dual mode, irq will be triggered at timeout / 2
> >>>> +	 * the real timeout occurs at timeout
> >>>> +	 */
> >>>> +	if (wdt_dev->pretimeout) {
> >>>> +		wdt_dev->pretimeout = timeout / 2;
> >>>
> >>> min_timeout is set to 1. I don't this works well if timeout == 1.
> >>> You'll either need to set min_timeout to 2, or handle that case.
> >> 
> >> It is appropriate to change min_timeout  to 2.
> >> 
> >>>
> >>>> +		timeout_interval = wdt_dev->pretimeout;
> >>>
> >>> timeout_interval is unnecessary. Just update timeout accordingly.
> >>> It needs to take the situation of timeout == 1 into account, though.
> 
> I plan to remove timeout_interval and directly use (timeout-pretimeout)
> update timeout.
> 
> >> 
> >> timeout represents the reset time. When the user calls timeout_show, 
> >> He hopes to get the configured timeout, not the value changed
> >> by pre-timeout.
> >> I modify it like this more in line with the original intention.
> >> 
> >>>
> >>>> +	}
> >>>>  	/*
> >>>>  	 * One bit is the value of 512 ticks
> >>>>  	 * The clock has 32 KHz
> >>>>  	 */
> >>>> -	reg = WDT_LENGTH_TIMEOUT(timeout << 6) | WDT_LENGTH_KEY;
> >>>> +	reg = WDT_LENGTH_TIMEOUT(timeout_interval << 6) | WDT_LENGTH_KEY;
> >>>>  	iowrite32(reg, wdt_base + WDT_LENGTH);
> >>>>  
> >>>>  	mtk_wdt_ping(wdt_dev);
> >>>> @@ -239,13 +248,46 @@ static int mtk_wdt_start(struct watchdog_device *wdt_dev)
> >>>>  		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 | WDT_MODE_DUAL_EN);
> >>>> +	else
> >>>> +		reg &= ~(WDT_MODE_IRQ_EN | WDT_MODE_DUAL_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)
> >>>> +{
> >>>> +	struct mtk_wdt_dev *mtk_wdt = watchdog_get_drvdata(wdd);
> >>>> +	void __iomem *wdt_base = mtk_wdt->wdt_base;
> >>>> +	u32 reg = ioread32(wdt_base + WDT_MODE);
> >>>> +
> >>>> +	if (timeout && !wdd->pretimeout) {
> >>>> +		wdd->pretimeout = wdd->timeout / 2;
> >>>> +		reg |= (WDT_MODE_IRQ_EN | WDT_MODE_DUAL_EN);
> >>>> +	} else if (!timeout && wdd->pretimeout) {
> >>>> +		wdd->pretimeout = 0;
> >>>> +		reg &= ~(WDT_MODE_IRQ_EN | WDT_MODE_DUAL_EN);
> >>>> +	} else
> >>>> +		return 0;

Please run your patch through checkpatch; the above results
in a note about a missing { }.

> >>>> +
> >>>> +	iowrite32(reg, wdt_base + WDT_MODE);
> >>>
> >>> What is the point of setting the mode here ? It will
> >>> be set again in mtk_wdt_set_timeout(). Seems to me all
> >>> you need to do here is to set wdd->pretimeout,
> >>> then call mtk_wdt_set_timeout().
> >> 
> >> mtk_wdt_set_timeout() only set timeout and ping().
> >> Here also need to config to the dualmode or not.
> >> 
> >Ah, you are correct. Sorry, I confused this with the start function.
> >That makes me wonder if it would be better to extract a separate
> >function, mtk_wdt_set_mode(), for that purpose. Thoughts ?
> 
> I have done this, but I found there is no good abstract method, 
> because wdt mode is used in combination, for example：
> WDT_MODE_EN is included in start(), and here is not.
> And the judgment of pretimeout here is also different.
> 
Ok, makes sense. Another minor comment above, though.

Thanks,
Guenter

> Thanks,
> Qing
> 
> >
> >Thanks,
> >Guenter
> >
> >> Thanks,
> >> Qing
> >>>
> >>> Guenter
> >>>
> >>>> +
> >>>> +	return mtk_wdt_set_timeout(wdd, wdd->timeout);
> >>>> +}
> >>>> +
> >>>> +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 +295,21 @@ 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 +318,7 @@ 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 +330,22 @@ 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 = WDT_MAX_TIMEOUT / 2;
> >>>> +	} 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;
> >>>>
> >>>
> >> 
> >> 
> >
> 
> 

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