From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 291CC352F95; Mon, 12 Jan 2026 13:56:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768226189; cv=none; b=Dr7rGzzhUirrwA8nv1T+so4laRjZcZIhDEhwgxTTAvbuyHCmBxCVbF0g++gTBmpXj/AqkCZG1nmVcPYpdeOjr+fr9D8hyo8cULLp4PCUcn0DsTd7efDPXyaYBRTukx6RV7DtTZp17mV880ft6eWRoYNs19hvcsvvkHV7Ol9yItM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768226189; c=relaxed/simple; bh=nTOWUyppmdziosK5hC+4lapcYTGSSnyVm7zOVtqp8M0=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=A5ROoZ+Zs+H90iHngDKjFV4/K1yRqcO1g4gFISsrPl7nlTts+GqPG8wpolY5GXxTU+8fNtJPP16WZiGgvuOz5RyPR+vQslX/y2Hx1x3kstpJSEroIKQmdAnO0BvYwEVEfzxBUHdw26Qf9p9HnvBlvt4h/pCRPOhgZtR+inLgPxA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=FeAocew6; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="FeAocew6" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CB2C6C16AAE; Mon, 12 Jan 2026 13:56:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1768226189; bh=nTOWUyppmdziosK5hC+4lapcYTGSSnyVm7zOVtqp8M0=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=FeAocew6ZwUQ24IpZZlNx4LFCD0z0wEn3RWO6QKKLw39I1ZGaKv5lLQ7VxeoLwh9t mVULJHsw/busSOvuV0gsKBLsZq57QjLORdfYnxR3UfAk1QKbv2xMXnZ8N0usEmfAiG 2DGzx4L3GD8K929oKD6CdXg4ZkSm9hNbPGvY8VpFeGNE3n9t82ge/XwqBovQ4uIDiO NZZeDhFhzTQo2t8Nf4XZn8HYtSXienGr5HIWQpxJiOvqbMMRgCPBq7BOCAuzXfEUdt bqCygXVSprM6U7QfwplXvLd+JVJfUaYYdYIvG03j4mmJ3rV7Ib7UUIODXNbY/s+mY0 oy8A+65dSKgoQ== Message-ID: Date: Mon, 12 Jan 2026 14:56:24 +0100 Precedence: bulk X-Mailing-List: imx@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/2] dt-bindings: watchdog: fsl-imx: document continue in low power mode To: Nandor Han Cc: wim@linux-watchdog.org, linux@roeck-us.net, robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org, shawnguo@kernel.org, s.hauer@pengutronix.de, kernel@pengutronix.de, festevam@gmail.com, linux-watchdog@vger.kernel.org, devicetree@vger.kernel.org, imx@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <20251229145000.421426-1-nandor.han@gehealthcare.com> <20251229145000.421426-3-nandor.han@gehealthcare.com> <20251230-hidden-okapi-of-reputation-6ef8be@quoll> <04d8766f-0f79-409b-9290-3170e99e9750@kernel.org> <493b1bac-2eae-4c78-9c07-801eaf954b04@gehealthcare.com> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 8bit On 08/01/2026 08:58, Nandor Han wrote: > > On 1/7/26 12:48, Krzysztof Kozlowski wrote: >> CAUTION: This email originated from outside of GE HealthCare. Only open links or attachments if you trust the sender. Report suspicious emails using Outlook’s “Report” button. >> >> On 07/01/2026 10:12, Nandor Han wrote: >>> On 12/30/25 14:34, Krzysztof Kozlowski wrote: >>>> CAUTION: This email originated from outside of GE HealthCare. Only open links or attachments if you trust the sender. Report suspicious emails using Outlook’s “Report” button. >>>> >>>> On Mon, Dec 29, 2025 at 04:50:00PM +0200, Nandor Han wrote: >>>>> Property "fsl,wdt-continue-in-low-power" allows the watchdog to continue >>>>> running in low power modes (STOP and DOZE). By default, the watchdog is >>>>> suspended in these modes. This property provides the option to keep the >>>>> watchdog active during low power states when needed. >>>> And why exactly would that be a DT property? If system is sleeping >>>> (assuming this is what you meant by low power), no one will pet the dog, >>>> thus watchdog makes no sense. >>> Thanks for the feedback Krzysztof and Guenter. >>> >>> In our case, low-power mode is disabled. However, we have identified that under certain conditions, >> If your system has low power mode disabled, then you do not need this >> property - you already know that watchdog must continue (or whatever you >> want to achieve here). >> >>> specifically during simulated high-load scenarios, the device becomes unresponsive because it enters >>> one of these power states. >> Device as watchdog? I really do not understand your explanations, but >> for sure system load is not relevant to DT property. >> >>>> Otherwise I fail to see how this is a hardware property and we do not >>>> accept SW properties (see writing bindings, numerous presentations). >>> Our system is based on the i.MX7D CPU and the watchdog peripheral supports the configuration: >>> >>> (From i.MX 7Dual Applications Processor Reference Manual, Rev. 1, 01/2018, page: 1174) >>> --- >>> WDZST >>> Watchdog Low Power. Determines the operation of the WDOG during low-power modes. This bit is write >>> once-only. >>> --- >>> Given that our system does not support low-power modes, we intend to enable the watchdog across all power >>> states to ensure the device can recover properly under these conditions. >> That's not what your property said. Your property said watchdog should >> continue in low power modes. So when system enters low power mode, how >> the watchdog petting would work? >> >> Now you claim you want to enable it in low power mode but you do not >> have low power mode? Does not make sense to me at all. >> >> Best regards, >> Krzysztof >> > Sorry if anything is unclear. I would try to explain the change from the driver's point of view. I want "logical" point of view, not driver's. > > According to i.MX7D Reference Manual, the watchdog controller allows, via the WDOGx_WCR register, control over whether the watchdog continues or suspends in: > > a)WAIT power state (bit 7: WDW) > b)STOP and DOSE power state(bit 0: WDZST). > > The current driver implementation provides a Device Tree binding `fsl,suspend-in-wait` for configuring case (a) and forces the watchdog to be suspended in case (b). > > My patch adds the ability to configure case (b) as well. Just because you want to do something in the driver is not yet justification we want it in DT. Why can't you enable it always? Why this is system load (!!!) dependent? Best regards, Krzysztof