linux-kernel - Re: [PATCH 2/2] dt-bindings: phy: lan966x: Add optional microchip,sx-tx/rx-inverted

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Message-ID: <20251113-sassy-slicer-5a1be0d99aa9@spud>
Date: Thu, 13 Nov 2025 19:13:24 +0000
From: Conor Dooley <conor@...nel.org>
To: Horatiu Vultur <horatiu.vultur@...rochip.com>
Cc: Krzysztof Kozlowski <krzk@...nel.org>, vkoul@...nel.org,
	kishon@...nel.org, robh@...nel.org, krzk+dt@...nel.org,
	conor+dt@...nel.org, linux-phy@...ts.infradead.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] dt-bindings: phy: lan966x: Add optional
 microchip,sx-tx/rx-inverted

On Thu, Nov 13, 2025 at 12:56:50PM +0100, Horatiu Vultur wrote:
> The 11/12/2025 18:32, Conor Dooley wrote:
> > On Wed, Nov 12, 2025 at 09:02:35AM +0100, Horatiu Vultur wrote:
> > > The 11/11/2025 17:39, Conor Dooley wrote:
> > > > On Tue, Nov 11, 2025 at 11:06:02AM +0100, Krzysztof Kozlowski wrote:
> > > > > On 11/11/2025 10:58, Horatiu Vultur wrote:
> > > > > > The 11/10/2025 18:43, Conor Dooley wrote:
> > > > > > 
> > > > > > Hi Conor,
> > > > > > 
> > > > > >> On Mon, Nov 10, 2025 at 12:05:36PM +0100, Horatiu Vultur wrote:
> > > > > >>> This allows to invert the N and P signals of the RX and TX Serdes
> > > > > >>> signals. This option allows the board designer to trace their signals
> > > > > >>> easier on the boards.
> > > > > >>
> > > > > >> Why can't this just be done in software, debugfs or something like that?
> > > > > >> Maybe it's just your description is poor, but sounds like the intention
> > > > > >> here is to just switch things around for debug purposes.
> > > > > > 
> > > > > > I don't think it should be done through debugfs. As this describes the
> > > > > > board layout and I don't think someone will want to change it at
> > > > > > runtime to see how things behave. So maybe the description is poor.
> > > > > 
> > > > > You said it is purely for hardware designer to trace signals, so sorry,
> > > > > but that's not DTs purpose.
> > > > 
> > > > If it is not purely some sort of debug helper, then please explain
> > > > better in your commit message.
> > > 
> > > Yes, I will do so because I don't see how this is a debug helper
> > > functionality. I see it as changing the polarity of some pins and there
> > 
> > The word "trace" here might be problematic? Maybe you meant something
> > like "lay out", but all of the use of the word tracing in electronics
> > that I have ever seen refers to troubleshooting - be that physically
> > following signals to see if there's degradation or things like the
> > trace framework in linux.
> 
> I understand, by trace I meant "lay out" the signals on the board.
> What do you think if I say something like this:
> 
> ---
> dt-bindings: phy: lan966x: Add optional microchip,sx-tx/rx-inverted
> 
> The lan966x has 3 integrated SerDess and for each of them it is possible
> to change the polarity of the P(possitive) and N(Negative) pins Serdes.
> By changing the polarity of both pins then the functionality of the pins
> will be inverted.
> ---
> 
> I have tried not to mention any 'lay out' or 'trace' not to make it
> confusing.


Yeah, I think that that is substantially better.

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