linux-kernel - Re: [PATCH 2/2] watchdog: rti: tweak min_hw_heartbeat

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Date:   Wed, 1 Jul 2020 17:36:24 +0300
From:   Tero Kristo <t-kristo@...com>
To:     Guenter Roeck <linux@...ck-us.net>
CC:     Jan Kiszka <jan.kiszka@...mens.com>, <wim@...ux-watchdog.org>,
        <linux-watchdog@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] watchdog: rti: tweak min_hw_heartbeat_ms to match
 initial allowed window

On 01/07/2020 16:34, Guenter Roeck wrote:
> On 6/30/20 10:50 PM, Tero Kristo wrote:
> [ ... ]
> 
>> Hardware supports changing the timeout value, however it only updates this during the next window (preload values are picked once user pings the watchdog.)
>>
> The current driver doesn't support or use that, though, since the start
> function is only called once to start the watchdog, and not at all if
> the watchdog is already running. So, if the bootloader sets the timeout
> to X, and the user sets a timeout of, say, X * 4, userspace will never
> ping the watchdog often enough. The driver will have to address that
> to support already-running watchdogs.

Yeah, I will modify that. I think I will just prevent changing the 
timeout if watchdog has been enabled from boot, it is probably cleanest 
approach. Unless I happen to come up with some sane way to change it on fly.

-Tero
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