linux-kernel - Re: [PATCH 2/2] dt-bindings: watchdog: fsl-imx: document continue in low power mode

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Message-ID: <e24ec822-4d13-4136-8fb6-1bc6cbaf8e20@gehealthcare.com>
Date: Wed, 7 Jan 2026 11:12:35 +0200
From: Nandor Han <nandor.han@...ealthcare.com>
To: Krzysztof Kozlowski <krzk@...nel.org>
Cc: wim@...ux-watchdog.org, linux@...ck-us.net, robh@...nel.org,
 krzk+dt@...nel.org, conor+dt@...nel.org, shawnguo@...nel.org,
 s.hauer@...gutronix.de, kernel@...gutronix.de, festevam@...il.com,
 linux-watchdog@...r.kernel.org, devicetree@...r.kernel.org,
 imx@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] dt-bindings: watchdog: fsl-imx: document continue in
 low power mode


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,
specifically during simulated high-load scenarios, the device becomes unresponsive because it enters
one of these power states.

> 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.

Regards,
Nandor