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

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Message-ID: <44feed5a-95a7-4baa-b17e-514c0f50dae6@kernel.org>
Date: Tue, 6 Aug 2024 10:03:00 +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 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.

> 
> If something is a wakeup-source for Partial-IO it usually is a
> wakeup-source for suspend to memory as well but not the other way
> around.

I understand, makes sense. The trouble is that your driver code does not
indicate any of this.

> 
> This is the reason why I added a property that lists the devicenodes
> that are capable of wakeup from Partial-IO.

This property looks purely to satisfy your driver design.

Best regards,
Krzysztof