linux-kernel - Re: [PATCH] watchdog: max77620: Add support for watchdog timer

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Message-ID: <5757DE51.6000201@nvidia.com>
Date:	Wed, 8 Jun 2016 14:28:57 +0530
From:	Laxman Dewangan <ldewangan@...dia.com>
To:	Guenter Roeck <linux@...ck-us.net>
CC:	<wim@...ana.be>, <linux-kernel@...r.kernel.org>,
	<linux-watchdog@...r.kernel.org>
Subject: Re: [PATCH] watchdog: max77620: Add support for watchdog timer

Hi Guenter,

Thanks for quick review. I will take care of most of comment.
I have one query fr following comment.

Thanks,
Laxman

On Tuesday 07 June 2016 11:26 PM, Guenter Roeck wrote:
> Hi,
>
> On Mon, Jun 06, 2016 at 05:22:44PM +0530, Laxman Dewangan wrote:
> +	/* Stop watchodog */
> +	ret = regmap_update_bits(wdt->rmap, MAX77620_REG_CNFGGLBL2,
> +				 MAX77620_WDTEN, 0);
> +	if (ret < 0) {
> +		dev_err(wdt->dev, "Failed to reset WDTEN: %d\n", ret);
> +		return ret;
> +	}
> Alternatively, you could set WDOG_HW_RUNNING to tell the watchdog core
> that the watchdog is already running. The watchdog core would then ping
> the watchdog until the watchdog device is opened.
>
> That would also require to tell the watchdog core about the current (or default)
> timeout, which doesn't seem to be set anywhere. That means it won't be set at all
> unless user space updates it explicitly. This is quite unusual. Is it on purpose
> or an oversight ? If it is on purpose, please explain.

OK, we have use cases where we have enabled the WDT in BL also. and keep 
runnign till kernel up.
Instead of stopping WDT, I can say that WDOG_HW_RUNING and current 
timeout can be read from the register.

Now, the WDT need to be ping periodically. Is there any flag which 
enabled the worker thread from core which will keep pinging till user 
space alive and activate the WDT?