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From:   Anand Moon <linux.amoon@gmail.com>
Date:   Tue, 21 Nov 2023 09:36:37 +0530
Message-ID: <CANAwSgQGhDMeHLFpe8gnM2c26CjqX8QHOL1GdHrZJSvnBj39bA@mail.gmail.com>
Subject: Re: [PATCH v3 1/2] dt-bindings: usb: Add the binding example for the
 Genesys Logic GL3523 hub
To:     Conor Dooley <conor@kernel.org>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Conor Dooley <conor+dt@kernel.org>,
        Icenowy Zheng <uwu@icenowy.me>, linux-usb@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
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Hi Conor,

On Mon, 20 Nov 2023 at 21:15, Conor Dooley <conor@kernel.org> wrote:
>
> On Sun, Nov 19, 2023 at 08:57:28PM +0530, Anand Moon wrote:
> > Hi Conor,
> >
> > On Sun, 19 Nov 2023 at 19:28, Conor Dooley <conor@kernel.org> wrote:
> > >
> > > On Sun, Nov 19, 2023 at 08:04:50AM +0530, Anand Moon wrote:
> > > > Add the binding example for the USB3.1 Genesys Logic GL3523
> > > > integrates with USB 3.1 Gen 1 Super Speed and USB 2.0 High-Speed
> > > > hub.
> > >
> > > But no comment in the commit message about the new property for the
> > > "peer hub". $subject saying "dt-bindings: usb: Add the binding example
> > > for the Genesys Logic GL3523 hub" is misleading when the meaningful
> > > parts of the patch are unrelated to the example.
> > >
> > > >
> > > > Signed-off-by: Anand Moon <linux.amoon@gmail.com>
> > > > ---
> > > > V3: fix the dt_binding_check error, added new example for Genesys GL3523
> > > > v2: added Genesys GL3523 binding
> > > > v1: none
> > > > ---
> > > >  .../bindings/usb/genesys,gl850g.yaml          | 63 +++++++++++++++++--
> > > >  1 file changed, 59 insertions(+), 4 deletions(-)
> > > >
> > > > diff --git a/Documentation/devicetree/bindings/usb/genesys,gl850g.yaml b/Documentation/devicetree/bindings/usb/genesys,gl850g.yaml
> > > > index ee08b9c3721f..f8e88477fa11 100644
> > > > --- a/Documentation/devicetree/bindings/usb/genesys,gl850g.yaml
> > > > +++ b/Documentation/devicetree/bindings/usb/genesys,gl850g.yaml
> > > > @@ -9,9 +9,6 @@ title: Genesys Logic USB hub controller
> > > >  maintainers:
> > > >    - Icenowy Zheng <uwu@icenowy.me>
> > > >
> > > > -allOf:
> > > > -  - $ref: usb-device.yaml#
> > > > -
> > > >  properties:
> > > >    compatible:
> > > >      enum:
> > > > @@ -27,12 +24,44 @@ properties:
> > > >
> > > >    vdd-supply:
> > > >      description:
> > > > -      the regulator that provides 3.3V core power to the hub.
> > > > +      phandle to the regulator that provides power to the hub.
> > > > +
> > > > +  peer-hub:
> > > > +    $ref: /schemas/types.yaml#/definitions/phandle
> > > > +    description:
> > > > +      phandle to the peer hub on the controller.
> > >
> > > What is this, why is it needed? Please explain it in your commit
> > > message.
> > >
> > Ok, GL3523 integrates Genesys Logic self-developed USB 3.1 Gen 1
> > Super Speed transmitter/receiver physical layer (PHY) and USB 2.0
> > High-Speed PHY
> >
> > peer-hub is used to cross-connect those phy nodes so that it can help
> > hub power on/off simultaneously.
>
> I said please explain it in your commit message, but on reflection I
> think that would be insufficient. Extending the description to explain
> what the peer-hub is would be great too. "peer hub on the controller"
> doesn't seem to make sense to me either, as the peer hub phandle is to
> another phy, not to the controller. I think that would probably also be
> resolved by explaining what the peer hub is in a more detailed manner.
>
> If this is purely a genesys thing, the property should grow a genesys,
> prefix also.
>
No, some USB Hub have combined phy for USB 3.x and USB 2.0 and have common
reset-gpios and power supply, peer-hub node helps connect the USB controller and
bring up the USB hub.

I was waiting for more feedback on these changes.
Once it's ok I will update with proper the commit message in v4.

Thanks
-Anand

> Cheers,
> Conor.