Message-ID: <c7cbdaaa-e786-4842-9346-e2fde998fde5@kernel.org>
Date: Thu, 4 Dec 2025 17:48:57 +0100
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Vladimir Oltean <vladimir.oltean@....com>, Vinod Koul <vkoul@...nel.org>,
 Jakub Kicinski <kuba@...nel.org>
Cc: netdev@...r.kernel.org, devicetree@...r.kernel.org,
 linux-phy@...ts.infradead.org, linux-kernel@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, linux-mediatek@...ts.infradead.org,
 Daniel Golle <daniel@...rotopia.org>,
 Horatiu Vultur <horatiu.vultur@...rochip.com>, Andrew Lunn <andrew@...n.ch>,
 Heiner Kallweit <hkallweit1@...il.com>, Russell King
 <linux@...linux.org.uk>, "David S. Miller" <davem@...emloft.net>,
 Eric Dumazet <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>,
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>,
 Kishon Vijay Abraham I <kishon@...nel.org>,
 Matthias Brugger <matthias.bgg@...il.com>,
 AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
 Eric Woudstra <ericwouds@...il.com>, Marek Beh√∫n
 <kabel@...nel.org>, Lee Jones <lee@...nel.org>,
 Patrice Chotard <patrice.chotard@...s.st.com>
Subject: Re: [PATCH net-next 5/9] phy: add phy_get_rx_polarity() and
 phy_get_tx_polarity()

On 04/12/2025 16:34, Vladimir Oltean wrote:
> On Mon, Dec 01, 2025 at 09:41:21AM +0100, Krzysztof Kozlowski wrote:
>> On 01/12/2025 09:37, Vinod Koul wrote:
>>> On 24-11-25, 20:01, Jakub Kicinski wrote:
>>>> On Sat, 22 Nov 2025 21:33:37 +0200 Vladimir Oltean wrote:
>>>>> Add helpers in the generic PHY folder which can be used using 'select
>>>>> GENERIC_PHY_COMMON_PROPS' from Kconfig, without otherwise needing to
>>>>> enable GENERIC_PHY.
>>>>>
>>>>> These helpers need to deal with the slight messiness of the fact that
>>>>> the polarity properties are arrays per protocol, and with the fact that
>>>>> there is no default value mandated by the standard properties, all
>>>>> default values depend on driver and protocol (PHY_POL_NORMAL may be a
>>>>> good default for SGMII, whereas PHY_POL_AUTO may be a good default for
>>>>> PCIe).
>>>>>
>>>>> Push the supported mask of polarities to these helpers, to simplify
>>>>> drivers such that they don't need to validate what's in the device tree
>>>>> (or other firmware description).
>>>>>
>>>>> The proposed maintainership model is joint custody between netdev and
>>>>> linux-phy, because of the fact that these properties can be applied to
>>>>> Ethernet PCS blocks just as well as Generic PHY devices. I've added as
>>>>> maintainers those from "ETHERNET PHY LIBRARY", "NETWORKING DRIVERS" and
>>>>> "GENERIC PHY FRAMEWORK".
>>>>
>>>> I dunno.. ain't no such thing as "joint custody" maintainership.
>>>> We have to pick one tree. Given the set of Ms here, I suspect 
>>>> the best course of action may be to bubble this up to its own tree.
>>>> Ask Konstantin for a tree in k.org, then you can "co-post" the patches
>>>> for review + PR link in the cover letter (e.g. how Tony from Intel
>>>> submits their patches). This way not networking and PHY can pull
>>>> the shared changes with stable commit IDs.
>>>
>>> How much is the volume of the changes that we are talking about, we can
>>> always ack and pull into each other trees..?
>>
>> That's just one C file, isn't it? Having dedicated tree for one file
>> feels like huge overhead.
> 
> I have to admit, no matter how we define what pertains to this presumed
> new git tree, the fact is that the volume of patches will be quite low.
> 
> Since the API provider always sits in drivers/phy/ in every case that I
> can think about, technically all situations can be resolved by linux-phy
> providing these stable PR branches to netdev. In turn, to netdev it
> makes no difference whether the branches are coming from linux-phy or a
> third git tree. Whereas to linux-phy, things would even maybe a bit
> simpler, due to already having the patches vs needing to pull them from
> the 3rd tree.
> 
> From my perspective, if I'm perfectly honest, the idea was attractive
> because of the phenomenal difference in turnaround times between netdev
> and linux-phy review&merge processes (very fast in netdev, very slow and
> patchy in linux-phy). If there's a set like this, where all API consumers
> are in netdev for now but the API itself is in linux-phy, you'd have to
> introduce 1000 NOP cycles just to wait for the PR branch.
> 
> In that sense, having more people into the mix would help just because
> there's more people (i.e. fewer points of failure), even though overall
> there's more overhead.
> 
> IDK, these are my 2 cents, I can resubmit this set in 2 weeks with the
> maintainership of the PHY common properties exclusive to linux-phy.


Jakub supported the idea, so I also do not oppose, and if that helps you
folks, then go ahead.

Best regards,
Krzysztof

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