Message-ID: <fa11631e-48f9-4e95-95c4-20b77cb0a1be@kernel.org>
Date: Thu, 5 Sep 2024 11:25:48 +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 11:15, Krzysztof Kozlowski wrote:
> 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.

I am going through this thread again to write something in DT BoF but
this is confusing:

"Partial-IO is a very low power mode"
"not able to do a wakeup from Partial-IO."
"wakeup-source for Partial-IO"

Are you waking up from Partial-IO or are you waking up into Partial-IO?

And why the devices which are configured as wakeup-source cannot wake up
from or for Partial-IO?

Best regards,
Krzysztof

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