linux-kernel - Re: [PATCH net-next 1/4] dt-bindings: net: document st,phy-wol property

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Message-ID: <38278e2a-5a1b-4908-907e-7d45a08ea3b7@foss.st.com>
Date: Mon, 21 Jul 2025 17:56:17 +0200
From: Gatien CHEVALLIER <gatien.chevallier@...s.st.com>
To: Andrew Lunn <andrew@...n.ch>
CC: Krzysztof Kozlowski <krzk@...nel.org>,
        Andrew Lunn
	<andrew+netdev@...n.ch>,
        "David S. Miller" <davem@...emloft.net>,
        Eric
 Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni
	<pabeni@...hat.com>, Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski
	<krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Maxime Coquelin
	<mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        Christophe Roullier <christophe.roullier@...s.st.com>,
        Heiner Kallweit
	<hkallweit1@...il.com>,
        Russell King <linux@...linux.org.uk>, Simon Horman
	<horms@...nel.org>,
        Tristram Ha <Tristram.Ha@...rochip.com>,
        Florian Fainelli
	<florian.fainelli@...adcom.com>,
        <netdev@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net-next 1/4] dt-bindings: net: document st,phy-wol
 property

Hello Andrew,

On 7/21/25 15:18, Andrew Lunn wrote:
> On Mon, Jul 21, 2025 at 02:10:48PM +0200, Gatien CHEVALLIER wrote:
>> Hello Krzysztof,
>>
>> On 7/21/25 13:30, Krzysztof Kozlowski wrote:
>>> On 21/07/2025 13:14, Gatien Chevallier wrote:
>>>> The "st,phy-wol" property can be set to use the wakeup capability of
>>>> the PHY instead of the MAC.
>>>
>>>
>>> And why would that be property of a SoC or board? Word "can" suggests
>>> you are documenting something which exists, but this does not exist.
>> Can you elaborate a bit more on the "not existing" part please?
>>
>> For the WoL from PHY to be supported, the PHY line that is raised
>> (On nPME pin for this case) when receiving a wake up event has to be
>> wired to a wakeup event input of the Extended interrupt and event
>> controller(EXTI), and that's implementation dependent.
> 
> How does this differ from normal interrupts from the PHY? Isn't the
> presence of an interrupt in DT sufficient to indicate the PHY can wake
> the system?
> 
> 	Andrew

Here's an extract from the Microchip datasheet for the LAN8742A PHY:

"In addition to the main interrupts described in this section, an nPME
pin is provided exclusively for WoL specific interrupts."

I'm not an expert of the different PHYs, but I guess there may be a
distinction needed between some "main" PHY interrupts and the WoL one
at least for deep low-power use cases.

Because this line is wired to a peripheral managed by our
TEE, the ultimate goal here would be to declare the OP-TEE node as
an interrupt provider and to forward the interrupt to the kernel using
the asynchronous notification mechanism. Then, reference the OP-TEE
node in the "interrupts-extended" property in the PHY node so that it
can be acked by the PHY driver. As of now, this patch set at least allow
to wakeup from a deep low power mode using the WoL capability of the
PHY.

Regarding this property, somewhat similar to "mediatek,mac-wol",
I need to position a flag at the mac driver level. I thought I'd go
using the same approach.

Best regards,
Gatien