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Thu, 20 Aug 2026 08:12:16 -0700 (PDT) Received: from dev-ag ([102.33.165.38]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-499b20bb2b4sm46102495e9.0.2026.08.20.08.12.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 20 Aug 2026 08:12:15 -0700 (PDT) From: Andrew Gaylard To: Guenter Roeck Cc: linux-watchdog@vger.kernel.org, xt.hu@cqplus1.com, wim@linux-watchdog.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH] watchdog: sunplus: fix sp_wdt_restart spin loop and timeout In-Reply-To: (Guenter Roeck's message of "Thu, 20 Aug 2026 06:42:30 -0700") References: <20260820125304.1583383-1-ag@ffroot.co.za> User-Agent: mu4e 1.12.14; emacs 30.2 Date: Thu, 20 Aug 2026 17:12:11 +0200 Message-ID: MIME-Version: 1.0 Content-Type: text/plain X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260820_081218_385334_CD6CC44D X-CRM114-Status: GOOD ( 13.40 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Guenter Roeck writes: > On Thu, Aug 20, 2026 at 02:53:04PM +0200, Andrew Gaylard wrote: >> sp_wdt_restart() returns immediately after writing WDT_RESUME. The >> kernel continues executing and the watchdog kthread could pet the >> watchdog before the short timeout expired, preventing reset. > > Is this observed behavior or just an assumption ? It's an assumption. >> Add a spin loop so no other CPU can pet the watchdog while waiting for >> the reset. Set the restart timeout to ~1.5s. > > I understand the first part, but why delay the reset by 1.5s ? > That is a functional change which needs an explanation. I had a printf there to confirm that it actually reached that point, so I needed the delay. -- Andrew