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

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Message-ID: <20160119065313.GA22443@vireshk>
Date:	Tue, 19 Jan 2016 12:23:13 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	Sandeep Tripathy <tripathy@...adcom.com>
Cc:	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 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);
        }


Please try if this works or not.

-- 
viresh