linux-kernel - Re: [PATCH v2 2/3] dt-bindings: watchdog: fsl-imx: document suspend in wait mode

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Message-ID: <3909608a-9725-5bfa-a9ac-ca7546479dc2@norik.com>
Date:   Thu, 27 Oct 2022 09:16:59 +0200
From:   Andrej Picej <andrej.picej@...ik.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        linux-watchdog@...r.kernel.org,
        Alexander Stein <alexander.stein@...tq-group.com>
Cc:     wim@...ux-watchdog.org, linux@...ck-us.net, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, shawnguo@...nel.org,
        s.hauer@...gutronix.de, kernel@...gutronix.de, festevam@...il.com,
        linux-imx@....com, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/3] dt-bindings: watchdog: fsl-imx: document suspend
 in wait mode

On 26. 10. 22 16:12, Krzysztof Kozlowski wrote:
> On 26/10/2022 02:38, Andrej Picej wrote:
>> On 25. 10. 22 15:48, Krzysztof Kozlowski wrote:
>>> On 25/10/2022 03:25, Andrej Picej wrote:
>>>> Property "fsl,suspend-in-wait" suspends watchdog in "WAIT" mode which
>>>> corresponds to Linux's Suspend-to-Idle S0 mode. If this property is not
>>>> set and the device is put into Suspend-to-Idle mode, the watchdog
>>>> triggers a reset after 128 seconds.
>>>>
>>>> Signed-off-by: Andrej Picej <andrej.picej@...ik.com>
>>>> Reviewed-by: Fabio Estevam <festevam@...il.com>
>>>> ---
>>>> Changes in v2:
>>>>    - add a commit message,
>>>>    - add a list of devices which support this functionality
>>>> ---
>>>>    .../bindings/watchdog/fsl-imx-wdt.yaml        | 22 +++++++++++++++++++
>>>>    1 file changed, 22 insertions(+)
>>>>
>>>> diff --git a/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.yaml b/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.yaml
>>>> index fb7695515be1..9289de97859b 100644
>>>> --- a/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.yaml
>>>> +++ b/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.yaml
>>>> @@ -55,6 +55,28 @@ properties:
>>>>          If present, the watchdog device is configured to assert its
>>>>          external reset (WDOG_B) instead of issuing a software reset.
>>>>    
>>>> +  fsl,suspend-in-wait:
>>>> +    $ref: /schemas/types.yaml#/definitions/flag
>>>> +    description: |
>>>> +      If present, the watchdog device is suspended in WAIT mode
>>>> +      (Suspend-to-Idle). Only supported on following devices:
>>>> +        - "fsl,imx25-wdt",
>>>
>>> You need to define such allow/disallow in allOf:if:then, instead. Like
>>> example-schema is doing for foo-supply, just disallow it for some types
>>> or use "if: not: ..."
>>
>> Sorry missed that. So something like that should be added?:
>>
>>> allOf:
>>>    - if:
>>>        not:
>>>          properties:
>>>            compatible:
>>>              contains:
>>>                enum:
>>>                  - fsl,imx25-wdt
>>>                  - fsl,imx35-wdt
>>>                  - fsl,imx50-wdt
>>>                  - fsl,imx51-wdt
>>>                  - fsl,imx53-wdt
>>>                  - fsl,imx6q-wdt
>>>                  - fsl,imx6sl-wdt
>>>                  - fsl,imx6sll-wdt
>>>                  - fsl,imx6sx-wdt
>>>                  - fsl,imx6ul-wdt
>>>                  - fsl,imx7d-wdt
>>>                  - fsl,imx8mm-wdt
>>>                  - fsl,imx8mn-wdt
>>>                  - fsl,imx8mp-wdt
>>>                  - fsl,imx8mq-wdt
>>>                  - fsl,vf610-wdt
> 
> Yes.
> 
>>>      then:
>>>        properties:
>>>          fsl,suspend-in-wait: false
>>
>> And I'm assuming I can then remove the supported devices list from
>> property description.
> 
> Yes.
> 
>>
>> Are you fine with this, so we don't have to split the compatible list
>> like Alexander suggested? Basically we have the same list of WDW
>> supported devices in the driver.
> 
> I don't know to what you refer.
> 
I'm referring to this comment by Alexander Stein: 
(https://lore.kernel.org/all/13126397.uLZWGnKmhe@steina-w/)

> So the models listed in Documentation/devicetree/bindings/watchdog/fsl-imx-
> wdt.yaml not supporting this feature are
> * fsl,imx21-wdt
> * fsl,imx27-wdt
> * fsl,imx31-wdt
> * fsl,ls1012a-wdt
> * fsl,ls1043a-wdt
> ?
> 
> But all models are listed as compatible to fsl,imx21-wdt. So there is 
> something wrong here. IMHO this sounds like the compatible list has to be 
> split and updated. Depending on that this feature can be detected. Maintaining 
> another list seems error prone to me.

Best regards,
Andrej.