Sender: Guenter Roeck <groeck7@gmail.com>
Subject: Re: [PATCH v2 3/4] dt-bindings: watchdog: da9062: add watchdog
 timeout mode
To:     Adam Thomson <Adam.Thomson.Opensource@diasemi.com>,
        Andrej Picej <andrej.picej@norik.com>
Cc:     Support Opensource <Support.Opensource@diasemi.com>,
        "wim@linux-watchdog.org" <wim@linux-watchdog.org>,
        "linux-watchdog@vger.kernel.org" <linux-watchdog@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "robh+dt@kernel.org" <robh+dt@kernel.org>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        "shawnguo@kernel.org" <shawnguo@kernel.org>,
        "s.hauer@pengutronix.de" <s.hauer@pengutronix.de>,
        "kernel@pengutronix.de" <kernel@pengutronix.de>,
        "festevam@gmail.com" <festevam@gmail.com>,
        "linux-imx@nxp.com" <linux-imx@nxp.com>,
        "linux-arm-kernel@lists.infradead.org" 
        <linux-arm-kernel@lists.infradead.org>
References: <20211130134242.3516619-1-andrej.picej@norik.com>
 <20211130134242.3516619-3-andrej.picej@norik.com>
 <4591cdd6-9a7b-cd1d-817d-8950c8976d10@roeck-us.net>
 <DB9PR10MB4652C8A69A6A3F38B93ED18880679@DB9PR10MB4652.EURPRD10.PROD.OUTLOOK.COM>
From:   Guenter Roeck <linux@roeck-us.net>
Message-ID: <dcd75a82-5837-8d78-0a9f-6e5b7eafff28@roeck-us.net>
Date:   Tue, 30 Nov 2021 08:40:17 -0800
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On 11/30/21 8:11 AM, Adam Thomson wrote:
> On Guenter Roeck wrote:
> 
>>> Document the watchdog timeout mode property. If this property is used
>>> the user can select what happens on watchdog timeout. Set this property
>>> to 1 to enable SHUTDOWN (the device resets), set it to 0 and the device
>>> will go to POWERDOWN on watchdog timeout.
>>>
>>> Signed-off-by: Andrej Picej <andrej.picej@norik.com>
>>> ---
>>>    Documentation/devicetree/bindings/watchdog/da9062-wdt.txt | 3 +++
>>>    1 file changed, 3 insertions(+)
>>>
>>> diff --git a/Documentation/devicetree/bindings/watchdog/da9062-wdt.txt
>> b/Documentation/devicetree/bindings/watchdog/da9062-wdt.txt
>>> index 950e4fba8dbc..e3e6e56cee21 100644
>>> --- a/Documentation/devicetree/bindings/watchdog/da9062-wdt.txt
>>> +++ b/Documentation/devicetree/bindings/watchdog/da9062-wdt.txt
>>> @@ -10,6 +10,9 @@ Optional properties:
>>>    - dlg,use-sw-pm: Add this property to disable the watchdog during suspend.
>>>    	Only use this option if you can't use the watchdog automatic suspend
>>>    	function during a suspend (see register CONTROL_B).
>>> +- dlg,wdt-sd: Set what happens on watchdog timeout. If this bit is set the
>>> +	watchdog timeout triggers SHUTDOWN, if cleared the watchdog triggers
>>> +	POWERDOWN. Can be 0 or 1.
>>>
>>
>> Why does it need a value ? Why not just bool ?
> 
> One argument might be that if the property isn't provided then the OTP
> configured value can persist without needing a FW change around this DT binding.
> 
> My belief though is that the majority of users would have this property set to 0
> by default in OTP, so a boolean would be OK I think here to enable watchdog
> shutdown.
> 

Sorry, you lost me.
	dlg,wdt-sd = <0>;
is the current situation, and identical to not having the property in
the first place.
	dlg,wdt-sd = <1>;
is new. I don't see the difference to
	dlg,wdt-sd;
vs. not having the property at all (which is, again, the current situation).
Since it has to be backward compatible,
	dlg,wdt-sd = <0>;
will always be identical to not having the property at all.
I can not find a situation where an integer would have any benefits over a boolean.

Guenter