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

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Message-ID: <20251112080235.c5iinfnketsunefy@DEN-DL-M31836.microchip.com>
Date: Wed, 12 Nov 2025 09:02:35 +0100
From: Horatiu Vultur <horatiu.vultur@...rochip.com>
To: Conor Dooley <conor@...nel.org>
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

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
are few examples in the devicetree bindings where pins change the
polarity. Why I see it as changing the polarity is because the
N(negative) will become P(positive) and the P(positive) will become the
N(negative), so we just invert the signals.

> pw-bot: changes-requested



-- 
/Horatiu