linux-kernel - Re: [PATCH v2 1/6] dt-bindings: ti, sci: Add property for partial-io-wakeup-sources

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Message-ID: <d2eb4faf-c723-453b-a9d8-68693c96fb42@kernel.org>
Date: Thu, 5 Sep 2024 11:15:49 +0200
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Markus Schneider-Pargmann <msp@...libre.com>
Cc: Nishanth Menon <nm@...com>, Tero Kristo <kristo@...nel.org>,
 Santosh Shilimkar <ssantosh@...nel.org>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Vignesh Raghavendra <vigneshr@...com>,
 Vibhore Vardhan <vibhore@...com>, Kevin Hilman <khilman@...libre.com>,
 Dhruva Gole <d-gole@...com>, linux-arm-kernel@...ts.infradead.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/6] dt-bindings: ti, sci: Add property for
 partial-io-wakeup-sources

On 05/09/2024 11:08, Markus Schneider-Pargmann wrote:
> On Tue, Aug 06, 2024 at 10:03:00AM GMT, Krzysztof Kozlowski wrote:
>> On 06/08/2024 09:11, Markus Schneider-Pargmann wrote:
>>> Hi Krzysztof,
>>>
>>> On Tue, Aug 06, 2024 at 08:18:01AM GMT, Krzysztof Kozlowski wrote:
>>>> On 29/07/2024 10:00, Markus Schneider-Pargmann wrote:
>>>>> Partial-IO is a very low power mode in which nearly everything is
>>>>> powered off. Only pins of a few hardware units are kept sensitive and
>>>>> are capable to wakeup the SoC. The device nodes are marked as
>>>>> 'wakeup-source' but so are a lot of other device nodes as well that are
>>>>> not able to do a wakeup from Partial-IO. This creates the need to
>>>>> describe the device nodes that are capable of wakeup from Partial-IO.
>>>>>
>>>>> This patch adds a property with a list of these nodes defining which
>>>>> devices can be used as wakeup sources in Partial-IO.
>>>>>
>>>>
>>>> <form letter>
>>>> This is a friendly reminder during the review process.
>>>>
>>>> It seems my or other reviewer's previous comments were not fully
>>>> addressed. Maybe the feedback got lost between the quotes, maybe you
>>>> just forgot to apply it. Please go back to the previous discussion and
>>>> either implement all requested changes or keep discussing them.
>>>>
>>>> Thank you.
>>>> </form letter>
>>>
>>> I tried to address your comment from last version by explaining more
>>> thoroughly what the binding is for as it seemed that my previous
>>> explanation wasn't really good.
>>>
>>> You are suggesting to use 'wakeup-source' exclusively. Unfortunately
>>> wakeup-source is a boolean property which covers two states. I have at
>>> least three states I need to describe:
>>>
>>>  - wakeup-source for suspend to memory and other low power modes
>>>  - wakeup-source for Partial-IO
>>>  - no wakeup-source
>>
>> Maybe we need generic property or maybe custom TI would be fine, but in
>> any case - whether device is wakeup and what sort of wakeup it is, is a
>> property of the device.
> 
> To continue on this, I currently only know of this Partial-IO mode that
> would require a special flag like this. So I think a custom TI property
> would work. For example a bool property like
> 
>   ti,partial-io-wakeup-source;
> 
> in the device nodes for which it is relevant? This would be in addition
> to the 'wakeup-source' property.

Rather oneOf. I don't think having two properties in a node brings any
more information.

I would suggest finding one more user of this and making the
wakeup-source an enum - either string or integer with defines in a header.

Best regards,
Krzysztof