Re: [PATCH v2 1/2] dt-bindings: usb: Introduce ITE IT5205 Alt. Mode Passive MUX

[AngeloGioacchino Del Regno]

Il 19/01/24 17:18, Conor Dooley ha scritto:
> On Fri, Jan 19, 2024 at 01:58:11PM +0100, AngeloGioacchino Del Regno wrote:
> > Introduce a binding for the ITE IT5205 Alternate Mode Passive MUX,
> > used for connecting, disconnecting and switching orientation and
> > control the SBU signals for alternate modes on USB Type-C ports.
> >
> > Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
> > ---
> >   .../devicetree/bindings/usb/ite,it5205.yaml   | 72 +++++++++++++++++++
> >   1 file changed, 72 insertions(+)
> >   create mode 100644 Documentation/devicetree/bindings/usb/ite,it5205.yaml
> >
> > diff --git a/Documentation/devicetree/bindings/usb/ite,it5205.yaml b/Documentation/devicetree/bindings/usb/ite,it5205.yaml
> > new file mode 100644
> > index 000000000000..36ec4251b5f2
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/usb/ite,it5205.yaml
> > @@ -0,0 +1,72 @@
> > +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/usb/ite,it5205.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: ITE IT5202 Type-C USB Alternate Mode Passive MUX
> > +
> > +maintainers:
> > +  - AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
> > +  - Tianping Fang <tianping.fang@xxxxxxxxxxxx>
> > +
> > +properties:
> > +  compatible:
> > +    const: ite,it5205
> > +
> > +  reg:
> > +    maxItems: 1
> > +
> > +  vcc-supply:
> > +    description: Power supply for VCC pin (3.3V)
> > +
> > +  mode-switch:
> > +    description: Flag the port as possible handle of altmode switching
> > +    type: boolean
> > +
> > +  orientation-switch:
> > +    description: Flag the port as possible handler of orientation switching
> > +    type: boolean
> > +
> > +  ite,ovp-enable:
> > +    description: Enable Over Voltage Protection functionality
> > +    type: boolean
>
> Bitta devil's advocacy perhaps, but why is this DT property? Is it not
> known whether or not this is supported based on the compatible, and
> whether or not to enable it is a decision for the operating system to
> make?

AFAIK, not all board designs can use the OVP. On some, this may be unstable - the
use case where this can be safely enabled is when there's nothing in between the
mux and the controller, and between the mux and the port.

Cheers,
Angelo