linux-kernel - Re: Re: [PATCH 3/3] arm64: dts: qcom: sa8540-ride: Enable first port of tertiary usb controller

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Date: Wed, 7 Feb 2024 03:32:03 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Andrew Halaney <ahalaney@...hat.com>
Cc: neil.armstrong@...aro.org, Krishna Kurapati <quic_kriskura@...cinc.com>, 
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>, Rob Herring <robh+dt@...nel.org>, 
	Bjorn Andersson <andersson@...nel.org>, Konrad Dybcio <konrad.dybcio@...aro.org>, 
	Conor Dooley <conor+dt@...nel.org>, linux-kernel@...r.kernel.org, 
	linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org, 
	quic_ppratap@...cinc.com, quic_jackp@...cinc.com
Subject: Re: Re: [PATCH 3/3] arm64: dts: qcom: sa8540-ride: Enable first port
 of tertiary usb controller

On Wed, 7 Feb 2024 at 02:10, Andrew Halaney <ahalaney@...hat.com> wrote:
>
> On Tue, Feb 06, 2024 at 03:30:32PM +0200, Dmitry Baryshkov wrote:
> > On Tue, 6 Feb 2024 at 15:28, <neil.armstrong@...aro.org> wrote:
> > >
> > > On 06/02/2024 12:47, Krishna Kurapati wrote:
> > > > From: Andrew Halaney <ahalaney@...hat.com>
> > > >
> > > > There is now support for the multiport USB controller this uses so
> > > > enable it.
> > > >
> > > > The board only has a single port hooked up (despite it being wired up to
> > > > the multiport IP on the SoC). There's also a USB 2.0 mux hooked up,
> > > > which by default on boot is selected to mux properly. Grab the gpio
> > > > controlling that and ensure it stays in the right position so USB 2.0
> > > > continues to be routed from the external port to the SoC.
> >
> > What is connected to the other port of the MUX?
>
> /me blows off the dust on the schematic
>
> It's a 1:2 mux, and one option is the out the board, the other
> is a test point I believe if I'm reading things right, although its not
> labeled so I'm not sure anyone would actually find it on the board.

Ack, this definitely looks like a static configuration.

>
> >
> > > >
> > > > Signed-off-by: Andrew Halaney <ahalaney@...hat.com>
> > > > Co-developed-by: Krishna Kurapati <quic_kriskura@...cinc.com>
> > > > Signed-off-by: Krishna Kurapati <quic_kriskura@...cinc.com>
> > > > ---
> > > >   arch/arm64/boot/dts/qcom/sa8540p-ride.dts | 21 +++++++++++++++++++++
> > > >   1 file changed, 21 insertions(+)
> > > >
> > > > diff --git a/arch/arm64/boot/dts/qcom/sa8540p-ride.dts b/arch/arm64/boot/dts/qcom/sa8540p-ride.dts
> > > > index b04f72ec097c..eed1ddc29bc1 100644
> > > > --- a/arch/arm64/boot/dts/qcom/sa8540p-ride.dts
> > > > +++ b/arch/arm64/boot/dts/qcom/sa8540p-ride.dts
> > > > @@ -503,6 +503,18 @@ &usb_2_qmpphy0 {
> > > >       status = "okay";
> > > >   };
> > > >
> > > > +&usb_2 {
> > > > +     pinctrl-0 = <&usb2_en>;
> > > > +     pinctrl-names = "default";
> > > > +
> > > > +     status = "okay";
> > > > +};
> > > > +
> > > > +&usb_2_dwc3 {
> > > > +     phy-names = "usb2-port0", "usb3-port0";
> > > > +     phys = <&usb_2_hsphy0>, <&usb_2_qmpphy0>;
> > > > +};
> > > > +
> > > >   &xo_board_clk {
> > > >       clock-frequency = <38400000>;
> > > >   };
> > > > @@ -655,4 +667,13 @@ wake-pins {
> > > >                       bias-pull-up;
> > > >               };
> > > >       };
> > > > +
> > > > +     usb2_en: usb2-en-state {
> > > > +             /* TS3USB221A USB2.0 mux select */
> > > > +             pins = "gpio24";
> > > > +             function = "gpio";
> > > > +             drive-strength = <2>;
> > > > +             bias-disable;
> > > > +             output-low;
> > > > +     };
> > > >   };
> > >
> > > Isn't gpio-hog the preferred way to describe that ?
> >
> > That depends. As this pinctrl describes board configuration, I'd agree
> > with Neil.
>
> I unfortunately don't have the experience with gpio-hog to weigh in
> here, but wouldn't be opposed to Krishna switching it if that's what's
> recommended for this type of thing.

Quoting gpio.txt:

The GPIO chip may contain GPIO hog definitions. GPIO hogging is a mechanism
providing automatic GPIO request and configuration as part of the
gpio-controller's driver probe function.

See sdm845-pinctrl.yaml for an example of the gpio-hog node.

>
> >
> >
> > --
> > With best wishes
> > Dmitry
> >
>


-- 
With best wishes
Dmitry