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From: Guenter Roeck <linux@roeck-us.net>
To: 1536943441 <1536943441@qq.com>,
	linux-watchdog <linux-watchdog@vger.kernel.org>
Cc: wim <wim@linux-watchdog.org>,
	linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: 回复： [PATCH] watchdog: sbsa-gwdt: clamp timeout before updating wdd->timeout
Date: Fri, 19 Dec 2025 07:41:07 -0800	[thread overview]
Message-ID: <39f2a3ac-6906-4970-822e-d1f5cdced563@roeck-us.net> (raw)
In-Reply-To: <tencent_8FC8A3A9BF39EB3529C9320DFC259E0CE607@qq.com>

On 12/19/25 01:46, 1536943441 wrote:
> Hi Guenter,
> 
> thank you for the detailed explanation.
> 
> I misunderstood the watchdog core semantics here. With max_hw_heartbeat_ms set, the userspace timeout can represent a virtual timeout and is not expected to be limited by the single hardware timeout. Given that, my change is indeed wrong
> and I will drop this patch.
> 
> One follow-up question: in my testing, "/sys/class/watchdog/watchdog0/max_timeout" always shows 0 for sbsa-gwdt.  Should the driver set wdd->max_timeout in probe(), or is a 0 value expected when max_hw_heartbeat_ms/virtual timeouts are used?
> 

The value is as expected, and the driver should not do anything. A value of 0
means "unlimited", which in practice means that the limit is UINT_MAX / 1000.

Turns out the attribute is not documented. We should add it to the ABI
documentation. If/when I find the time ...

Thanks,
Guenter


      parent reply	other threads:[~2025-12-19 15:41 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-12-18  2:31 Zhu Ling
2025-12-18  4:53 ` Guenter Roeck
     [not found]   ` <tencent_8FC8A3A9BF39EB3529C9320DFC259E0CE607@qq.com>
2025-12-19 15:41     ` Guenter Roeck [this message]

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