linux-kernel - Re: [PATCH] watchdog: wdat_wdt: Set the min and max timeout values properly

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Message-ID: <Yu4DssMsVUP2Oee7@lahna>
Date:   Sat, 6 Aug 2022 09:01:22 +0300
From:   Mika Westerberg <mika.westerberg@...ux.intel.com>
To:     Jean Delvare <jdelvare@...e.de>
Cc:     linux-watchdog@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Guenter Roeck <linux@...ck-us.net>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
Subject: Re: [PATCH] watchdog: wdat_wdt: Set the min and max timeout values
 properly

On Sat, Aug 06, 2022 at 12:07:06AM +0200, Jean Delvare wrote:
> The wdat_wdt driver is misusing the min_hw_heartbeat_ms field. This
> field should only be used when the hardware watchdog device should not
> be pinged more frequently than a specific period. The ACPI WDAT
> "Minimum Count" field, on the other hand, specifies the minimum
> timeout value that can be set. This corresponds to the min_timeout
> field in Linux's watchdog infrastructure.
> 
> Setting min_hw_heartbeat_ms instead can cause pings to the hardware
> to be delayed when there is no reason for that, eventually leading to
> unexpected firing of the watchdog timer (and thus unexpected reboot).
> 
> I'm also changing max_hw_heartbeat_ms to max_timeout for symmetry,
> although the use of this one isn't fundamentally wrong, but there is
> also no reason to enable the software-driven ping mechanism for the
> wdat_wdt driver.
> 
> Signed-off-by: Jean Delvare <jdelvare@...e.de>
> Fixes: 058dfc767008 ("ACPI / watchdog: Add support for WDAT hardware watchdog")
> Cc: Wim Van Sebroeck <wim@...ux-watchdog.org>
> Cc: Guenter Roeck <linux@...ck-us.net>
> Cc! Mika Westerberg <mika.westerberg@...ux.intel.com>

Reviewed-by: Mika Westerberg <mika.westerberg@...ux.intel.com>