linux-kernel - Re: [PATCH 1/1] watchdog: sp805: ping fails to abort wdt reset

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Message-ID: <20160119071723.GB22443@vireshk>
Date:	Tue, 19 Jan 2016 12:47:23 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	Guenter Roeck <linux@...ck-us.net>
Cc:	Sandeep Tripathy <tripathy@...adcom.com>, wim@...ana.be,
	linux-watchdog@...r.kernel.org, linux-kernel@...r.kernel.org,
	bcm-kernel-feedback-list@...adcom.com
Subject: Re: [PATCH 1/1] watchdog: sp805: ping fails to abort wdt reset

On 18-01-16, 23:11, Guenter Roeck wrote:
> On 01/18/2016 10:53 PM, Viresh Kumar wrote:
> >On 19-01-16, 11:34, Sandeep Tripathy wrote:
> >>  sp805 wdt asserts interrupt for the first expiry and
> >
> >Why an extra space before sp805 ?
> >
> >>reloads the counter. If wdt interrupt is set and count
> >>reaches zero then wdt reset event is generated.To get
> >
> >Add space after full-stop.
> >
> >>wdt reset at t timeout the driver loads wdt counter
> >
> >Keep t and t/2 in single quotes, its hardly readable otherwise.
> >
> >>with t/2. A ping before t second *should* prevent wdt
> >>reset. Currently if ping is done after t/2 sec then
> >>wdt interrupt condition gets set. On the next countdown
> >>of loadval wdt reset event occurs eventhough wdt was
> >>reloaded before the set timeout t.
> >>
> >>  This patch clears the interrupt condition on ping.
> >
> >Why extra spaces before 'This'?
> >
> >>
> >>Signed-off-by: Sandeep Tripathy <tripathy@...adcom.com>
> >>---
> >>  drivers/watchdog/sp805_wdt.c |    5 ++---
> >>  1 file changed, 2 insertions(+), 3 deletions(-)
> >>
> >>diff --git a/drivers/watchdog/sp805_wdt.c b/drivers/watchdog/sp805_wdt.c
> >>index 01d8162..e7a715e 100644
> >>--- a/drivers/watchdog/sp805_wdt.c
> >>+++ b/drivers/watchdog/sp805_wdt.c
> >>@@ -139,12 +139,11 @@ static int wdt_config(struct watchdog_device *wdd, bool ping)
> >>
> >>  	writel_relaxed(UNLOCK, wdt->base + WDTLOCK);
> >>  	writel_relaxed(wdt->load_val, wdt->base + WDTLOAD);
> >>+	writel_relaxed(INT_MASK, wdt->base + WDTINTCLR);
> >>
> >>-	if (!ping) {
> >>-		writel_relaxed(INT_MASK, wdt->base + WDTINTCLR);
> >>+	if (!ping)
> >>  		writel_relaxed(INT_ENABLE | RESET_ENABLE, wdt->base +
> >>  				WDTCONTROL);
> >>-	}
> >>
> >>  	writel_relaxed(LOCK, wdt->base + WDTLOCK);
> >
> >If I read the TRM properly, then you don't need to load the WDTLOAD
> >register on ping and so your change can be written as:
> >
> >diff --git a/drivers/watchdog/sp805_wdt.c b/drivers/watchdog/sp805_wdt.c
> >index 01d816251302..42e1ec86532d 100644
> >--- a/drivers/watchdog/sp805_wdt.c
> >+++ b/drivers/watchdog/sp805_wdt.c
> >@@ -138,10 +138,10 @@ static int wdt_config(struct watchdog_device *wdd, bool ping)
> >         spin_lock(&wdt->lock);
> >
> >         writel_relaxed(UNLOCK, wdt->base + WDTLOCK);
> >-       writel_relaxed(wdt->load_val, wdt->base + WDTLOAD);
> >+       writel_relaxed(INT_MASK, wdt->base + WDTINTCLR);
> >
> >         if (!ping) {
> >-               writel_relaxed(INT_MASK, wdt->base + WDTINTCLR);
> >+               writel_relaxed(wdt->load_val, wdt->base + WDTLOAD);
> >                 writel_relaxed(INT_ENABLE | RESET_ENABLE, wdt->base +
> >                                 WDTCONTROL);
> >         }
> >
> 
> That would require additional changes. Reason is that the load value is not immediately
> written after a timeout change, but only with the next ping (which happens immediately
> afterwards). With your proposed change, the load value would never be updated.
> 
> Besides, that would be a separate change, and would require a separate patch.

Hmm, maybe then we can keep the original patch as is :)

@Sandeep: Please resend your patch after fixing the commit log and not
the diff.

-- 
viresh