linux-kernel - Re: [PATCH v6 1/5] dt-bindings: usb: Add binding for Realtek RTS5411 hub controller

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Message-ID: <YG+IcUvJPAa3NieK@google.com>
Date:   Thu, 8 Apr 2021 15:49:21 -0700
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Rob Herring <robh@...nel.org>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Alan Stern <stern@...land.harvard.edu>,
        Frank Rowand <frowand.list@...il.com>,
        linux-kernel@...r.kernel.org,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Douglas Anderson <dianders@...omium.org>,
        Peter Chen <peter.chen@....com>,
        Michal Simek <michal.simek@...inx.com>,
        linux-usb@...r.kernel.org,
        Ravi Chandra Sadineni <ravisadineni@...omium.org>,
        Bastien Nocera <hadess@...ess.net>, devicetree@...r.kernel.org,
        Stephen Boyd <swboyd@...omium.org>
Subject: Re: [PATCH v6 1/5] dt-bindings: usb: Add binding for Realtek RTS5411
 hub controller

On Tue, Apr 06, 2021 at 11:30:01AM -0500, Rob Herring wrote:
> On Mon, Apr 05, 2021 at 01:18:13PM -0700, Matthias Kaehlcke wrote:
> > The Realtek RTS5411 is a USB 3.0 hub controller with 4 ports.
> > 
> > This initial version of the binding only describes USB related
> > aspects of the RTS5411, it does not cover the option of
> > connecting the controller as an i2c slave.
> > 
> > Signed-off-by: Matthias Kaehlcke <mka@...omium.org>
> > ---
> > 
> > Changes in v7:
> > - added type ref for 'companion-hub' property
> > 
> > Changes in v6:
> > - Realtek binding instead of generic onboard_usb_hub
> > - added 'companion-hub' property
> > - added reference to 'usb-device.yaml'
> > - 'fixed' indentation of compatible entries to keep yamllint happy
> > - added 'additionalProperties' entry
> > - updated commit message
> > 
> > Changes in v5:
> > - updated 'title'
> > - only use standard USB compatible strings
> > - deleted 'usb_hub' node
> > - renamed 'usb_controller' node to 'usb-controller'
> > - removed labels from USB nodes
> > - added 'vdd-supply' to USB nodes
> > 
> > Changes in v4:
> > - none
> > 
> > Changes in v3:
> > - updated commit message
> > - removed recursive reference to $self
> > - adjusted 'compatible' definition to support multiple entries
> > - changed USB controller phandle to be a node
> > 
> > Changes in v2:
> > - removed 'wakeup-source' and 'power-off-in-suspend' properties
> > - consistently use spaces for indentation in example
> > 
> >  .../bindings/usb/realtek,rts5411.yaml         | 59 +++++++++++++++++++
> >  1 file changed, 59 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/usb/realtek,rts5411.yaml
> > 
> > diff --git a/Documentation/devicetree/bindings/usb/realtek,rts5411.yaml b/Documentation/devicetree/bindings/usb/realtek,rts5411.yaml
> > new file mode 100644
> > index 000000000000..b59001972749
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/usb/realtek,rts5411.yaml
> > @@ -0,0 +1,59 @@
> > +# SPDX-License-Identifier: GPL-2.0-only or BSD-2-Clause
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/usb/realtek,rts5411.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Binding for the Realtek RTS5411 USB 3.0 hub controller
> > +
> > +maintainers:
> > +  - Matthias Kaehlcke <mka@...omium.org>
> > +
> > +allOf:
> > +  - $ref: usb-device.yaml#
> > +
> > +properties:
> > +  compatible:
> > +    items:
> > +      - enum:
> > +          - usbbda,5411
> > +          - usbbda,411
> > +
> 
> reg: true
> 
> to fix the error.

Will fix in v8 (this is v7, even though the subject says otherwise,
I forgot to increment the version number when sending).

> > +  vdd-supply:
> > +    description:
> > +      phandle to the regulator that provides power to the hub.
> > +
> > +  companion-hub:
> > +    $ref: '/schemas/types.yaml#/definitions/phandle'
> > +    description:
> > +      phandle to the companion hub on the controller.
> 
> This should be required I think. I suppose you could only hook up 2.0
> ports, but why. And 3.0 only wouldn't be USB compliant, would it?

Agreed, that makes sense now that this is a specific binding for the
RTS5411. It seems unlikely that a system would use a USB 3.0 capable
hub on a USB 2.0 controller, and as you said 3.0 only wouldn't be USB
compliant.

I made the attribute initially optional because the binding was
intended to be generic (bad idea), and for certain hubs a required
'companion-hub' wouldn't make sense (e.g. USB 2.0 only).

> > +
> > +required:
> > +  - compatible
> > +  - reg
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > +  - |
> > +    usb-controller {
> 
> 'usb' is the standard name.

ack

Thanks for your comments!

m.