Sender: Guenter Roeck <groeck7@gmail.com>
Subject: Re: [PATCH 1/2] watchdog: imx2_wdg: Alow ping on suspend
To:     Stefan Wahren <stefan.wahren@i2se.com>,
        Alistair Francis <alistair@alistair23.me>,
        linux-kernel@vger.kernel.org, shawnguo@kernel.org,
        wim@linux-watchdog.org, linux-watchdog@vger.kernel.org,
        s.hauer@pengutronix.de, linux-arm-kernel@lists.infradead.org
Cc:     linux-imx@nxp.com, kernel@pengutronix.de, festevam@gmail.com,
        devicetree@vger.kernel.org, robh+dt@kernel.org
References: <20220109114120.386013-1-alistair@alistair23.me>
 <20220109114120.386013-2-alistair@alistair23.me>
 <4c5df296-b930-f65f-1106-c00889f1cdc1@i2se.com>
From:   Guenter Roeck <linux@roeck-us.net>
Message-ID: <4c3056df-2ae6-04d7-30cb-cd478f089266@roeck-us.net>
Date:   Thu, 13 Jan 2022 11:43:07 -0800
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On 1/13/22 10:55 AM, Stefan Wahren wrote:
> Hi,
> 
> Am 09.01.22 um 12:41 schrieb Alistair Francis:
>> The i.MX watchdog cannot be disabled by softwrae once it has been
> s/softwrae/software/
>> enabled. This means that it can't be stopped before suspend.
>>
>> For systems that enter low power mode this is fine, as the watchdog will
>> be automatically stopped by hardwrae in low power mode. Not all i.MX
> s/hardwrae/hardware/
>> platforms support low power mode in the mainline kernel. For example the
>> i.MX7D does not enter low power mode and so will be rebooted 2 minutes
>> after entering freeze or mem sleep states.
>>
>> This patch introduces a device tree property "fsl,ping-during-suspend"
>> that can be used to enable ping on suspend support for these systems.
> 
> Introducing vendor specific properties for Linux behavior should be
> avoided. The DT should describe just the hardware.
> 
> In case i.mx7d is affected, how about enabling this workaround for
> compatible fsl,imx7d-wdt? This has the advantage that in case low power
> mode will be implemented
> <https://elixir.bootlin.com/linux/latest/B/ident/fsl%2Cimx7d-wdt>, we
> don't have to care about DTB files.
> 

Agreed.

Guenter