lkml.org 
[lkml]   [2022]   [Jun]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH v5 1/9] dt-bindings: usb: Add Type-C switch binding
On Thu, Jun 23, 2022 at 11:30 AM Stephen Boyd <swboyd@chromium.org> wrote:
>
> Quoting Prashant Malani (2022-06-22 10:34:30)
> > diff --git a/Documentation/devicetree/bindings/usb/typec-switch.yaml b/Documentation/devicetree/bindings/usb/typec-switch.yaml
> > new file mode 100644
> > index 000000000000..78b0190c8543
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/usb/typec-switch.yaml
> > @@ -0,0 +1,74 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/usb/typec-switch.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: USB Type-C Switch
> > +
> > +maintainers:
> > + - Prashant Malani <pmalani@chromium.org>
> > +
> > +description:
> > + A USB Type-C switch represents a component which routes USB Type-C data
> > + lines to various protocol host controllers (e.g USB, VESA DisplayPort,
> > + Thunderbolt etc.) depending on which mode the Type-C port, port partner
> > + and cable are operating in. It can also modify lane routing based on
> > + the orientation of a connected Type-C peripheral.
> > +
> > +properties:
> > + compatible:
> > + const: typec-switch
> > +
> > + mode-switch:
> > + type: boolean
> > + description: Specify that this switch can handle alternate mode switching.
> > +
> > + orientation-switch:
> > + type: boolean
> > + description: Specify that this switch can handle orientation switching.
> > +
> > + ports:
> > + $ref: /schemas/graph.yaml#/properties/ports
> > + description: OF graph binding modelling data lines to the Type-C switch.
> > +
> > + properties:
> > + port@0:
> > + $ref: /schemas/graph.yaml#/properties/port
> > + description: Link between the switch and a Type-C connector.
>
> Is there an update to the usb-c-connector binding to accept this port
> connection?

Not at this time. I don't think we should enforce that either.
(Type-C data-lines could theoretically be routed through intermediate
hardware like retimers/repeaters)

>
> > +
> > + required:
> > + - port@0
> > +
> > +required:
> > + - compatible
> > + - ports
> > +
> > +anyOf:
> > + - required:
> > + - mode-switch
> > + - required:
> > + - orientation-switch
> > +
> > +additionalProperties: true
> > +
> > +examples:
> > + - |
> > + drm-bridge {
> > + usb-switch {
> > + compatible = "typec-switch";
>
> I still don't understand the subnode design here. usb-switch as a
> container node indicates to me that this is a bus, but in earlier rounds
> of this series it was stated this isn't a bus.

I am not aware of this as a requirement. Can you please point me to the
documentation that states this needs to be the case?

> Why doesn't it work to
> merge everything inside usb-switch directly into the drm-bridge node?

I attempted to explain the rationale in the previous version [1], but
using a dedicated sub-node means the driver doesn't haven't to
inspect individual ports to determine which of them need switches
registered for them. If it sees a `typec-switch`, it registers a
mode-switch and/or orientation-switch. IMO it simplifies the hardware
device binding too.

It also maps with the internal block diagram for these hardware
components (for ex. the anx7625 crosspoint switch is a separate
sub-block within anx7625).

[1] https://lore.kernel.org/linux-usb/CACeCKaeH6qTTdG_huC4yw0xxG8TYEOtfPW3tiVNwYs=P4QVPXg@mail.gmail.com/

>
> > + mode-switch;
> > + orientation-switch;
> > + ports {
> > + #address-cells = <1>;
> > + #size-cells = <0>;
> > +
> > + port@0 {
> > + reg = <0>;
> > + anx_ep: endpoint {
> > + remote-endpoint = <&typec_controller>;
> > + };
> > + };
> > + };
> > + };

\
 
 \ /
  Last update: 2022-06-23 21:36    [W:1.928 / U:0.128 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site