linux-kernel - Re: [PATCH 1/2] dt-bindings: usb: qcom,pmic-typec: drop port description

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Message-ID: <20240322183614.GA1233803-robh@kernel.org>
Date: Fri, 22 Mar 2024 13:36:14 -0500
From: Rob Herring <robh@...nel.org>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc: Bryan O'Donoghue <bryan.odonoghue@...aro.org>,
	neil.armstrong@...aro.org, Bjorn Andersson <andersson@...nel.org>,
	Konrad Dybcio <konrad.dybcio@...aro.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
	Conor Dooley <conor+dt@...nel.org>, linux-arm-msm@...r.kernel.org,
	linux-usb@...r.kernel.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] dt-bindings: usb: qcom,pmic-typec: drop port
 description

On Fri, Mar 22, 2024 at 05:49:00PM +0200, Dmitry Baryshkov wrote:
> On Fri, 22 Mar 2024 at 17:23, Bryan O'Donoghue
> <bryan.odonoghue@...aro.org> wrote:
> >
> > On 22/03/2024 15:09, neil.armstrong@...aro.org wrote:
> > >> TBH I think we should drop this HS, SS stuff from the connector
> > >> definition - there's nothing to say in a h/w definition anywhere HS
> > >> must be a port or indeed SS - not all hardware knows or cares about
> > >> different HS/SS signalling.
> > >
> > > It matches the USB-C connector electrical characteristics, which by spec
> > > has, at least:
> > > - High-Speed USB Line
> > > - up to 4 differential high-speed lanes that can be switched to DP, USB2
> > > or PCIe
> > > - SideBand line (SBU)
> > >
> > > And those 3 components can be handled by 3 different HW in the SoC, so
> > > each one has a dedicated port.
> > >
> > > Remember DT describes the HW, not the SW implementation.
> > >
> > > Neil
> >
> > Yes, you're right about that.
> >
> > I suppose
> >
> > 1. Orientation switches should be defined as coming from a port on the
> >     connector associated with the CC pins.
> >     port@3:
> >     orientation-switch port name goes here
> >
> > 2. Data-role switches...
> >     Again the CC pins
> >
> > https://community.silabs.com/s/article/what-s-the-role-of-cc-pin-in-type-c-solution?language=en_US
> >
> > Maybe the right-thing-to-do is to add another port for the CC pins -
> > which would still describe the hardware characteristics but would
> > _accurately_ name the thing which does the data-role/orientation switching
> 
> It's true that we don't describe CC lines. However In most of the
> cases CC lines are handled by the Type-C port manager directly. So
> there will be a connection from usb-c-connector to the pmic-typec
> itself (which looks pretty redundant).

The thought at the time this was designed was that would be the parent 
node of the connector. That's perhaps too simple.

Rob