linux-kernel - Re: [PATCH] watchdog: pnx4008: readout watchddog state

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Date:   Thu, 11 Apr 2019 09:03:05 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Alexandre Belloni <alexandre.belloni@...tlin.com>
Cc:     Vladimir Zapolskiy <vz@...ia.com>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Sylvain Lemieux <slemieux.tyco@...il.com>,
        Gregory Clement <gregory.clement@...tlin.com>,
        linux-arm-kernel@...ts.infradead.org,
        linux-watchdog@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] watchdog: pnx4008: readout watchddog state

Hi Alexandre,

On Thu, Apr 11, 2019 at 05:36:46PM +0200, Alexandre Belloni wrote:
> Readout the enabled state so it is possible to get the pre-userspace
> handler working. Also, avoid disabling the watchdog when nowayout is set to
> ensure the watchdog continues working and triggers if there is an issue
> later in the boot or if userspace fails to start.
> 
> Signed-off-by: Alexandre Belloni <alexandre.belloni@...tlin.com>
> ---
>  drivers/watchdog/pnx4008_wdt.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/watchdog/pnx4008_wdt.c b/drivers/watchdog/pnx4008_wdt.c
> index 8e261799c84e..9e3714e3814c 100644
> --- a/drivers/watchdog/pnx4008_wdt.c
> +++ b/drivers/watchdog/pnx4008_wdt.c
> @@ -209,7 +209,11 @@ static int pnx4008_wdt_probe(struct platform_device *pdev)
>  	watchdog_set_nowayout(&pnx4008_wdd, nowayout);
>  	watchdog_set_restart_priority(&pnx4008_wdd, 128);
>  
> -	pnx4008_wdt_stop(&pnx4008_wdd);	/* disable for now */
> +	if (readl(WDTIM_CTRL(wdt_base)) & COUNT_ENAB)
> +		set_bit(WDOG_HW_RUNNING, &pnx4008_wdd.status);
> +
> +	if (!nowayout)
> +		pnx4008_wdt_stop(&pnx4008_wdd);	/* disable for now */

I don't see the point of stopping the watchdog here, even though that is the
old behavior. If it is possible to detect that the watchdog is running, we
can let the core handle pings until the watchdog device is opened. The code
above does that, but only if nowayout is set. That seems inconsistent and
unnecessary. Is there a downside to doing that unconditionally ?

Nitpick: s/watchddog/watchdog/ in subject line.

Thanks,
Guenter

>  
>  	ret = watchdog_register_device(&pnx4008_wdd);
>  	if (ret < 0) {
> -- 
> 2.20.1
>