linux-kernel - Re: [PATCH RFC 03/22] dt-bindings: phy: Add Apple Type-C PHY

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Message-ID: <CAL_JsqL=y2OT4YrzT8z0O0T2hpM5X1k2pFEb8XjBRPoNMdO5kw@mail.gmail.com>
Date: Thu, 21 Aug 2025 18:00:27 -0500
From: Rob Herring <robh@...nel.org>
To: Janne Grunau <j@...nau.net>
Cc: Sven Peter <sven@...nel.org>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Felipe Balbi <balbi@...nel.org>, Alyssa Rosenzweig <alyssa@...enzweig.io>, Neal Gompa <neal@...pa.dev>, 
	Vinod Koul <vkoul@...nel.org>, Kishon Vijay Abraham I <kishon@...nel.org>, 
	Thinh Nguyen <Thinh.Nguyen@...opsys.com>, 
	Heikki Krogerus <heikki.krogerus@...ux.intel.com>, Philipp Zabel <p.zabel@...gutronix.de>, 
	linux-usb@...r.kernel.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, asahi@...ts.linux.dev, 
	linux-arm-kernel@...ts.infradead.org, linux-phy@...ts.infradead.org
Subject: Re: [PATCH RFC 03/22] dt-bindings: phy: Add Apple Type-C PHY

On Thu, Aug 21, 2025 at 11:33 AM Janne Grunau <j@...nau.net> wrote:
>
> On Thu, Aug 21, 2025 at 03:38:55PM +0000, Sven Peter wrote:
> > Apple's Type-C PHY (ATCPHY) is a PHY for USB 2.0, USB 3.x,
> > USB4/Thunderbolt, and DisplayPort connectivity found in Apple Silicon
> > SoCs.
> >
> > The PHY handles muxing between these different protocols and also provides
> > the reset controller for the attached dwc3 USB controller.
> >
> > Signed-off-by: Sven Peter <sven@...nel.org>
> > ---
> >  .../devicetree/bindings/phy/apple,atcphy.yaml      | 210 +++++++++++++++++++++
> >  MAINTAINERS                                        |   1 +
> >  2 files changed, 211 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/phy/apple,atcphy.yaml b/Documentation/devicetree/bindings/phy/apple,atcphy.yaml
> > new file mode 100644
> > index 0000000000000000000000000000000000000000..eb14010557c94f313b54b528e2d4039fe540062a
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/phy/apple,atcphy.yaml
> > @@ -0,0 +1,210 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/phy/apple,atcphy.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Apple Type-C PHY (ATCPHY)
> > +
> > +maintainers:
> > +  - Sven Peter <sven@...nel.org>
> > +
> > +description:
> > +  The Apple Type-C PHY (ATCPHY) is a PHY for USB 2.0, USB 3.x,
> > +  USB4/Thunderbolt, and DisplayPort connectivity found in Apple Silicon SoCs.
> > +
> > +  The PHY handles muxing between these different protocols and also provides the
> > +  reset controller for the attached dwc3 USB controller.
> > +
> > +  The PHY is designed for USB4 operation and does not handle individual
> > +  differential pairs as distinct DisplayPort lanes. Any reference to lane in
> > +  this binding hence refers to two differential pairs (RX and TX) as used in USB
> > +  terminology.
> > +
> > +properties:
> > +  compatible:
> > +    enum:
> > +      - apple,t6000-atcphy
> > +      - apple,t6000-atcphy-dp-only # PHY hardwired to DP-to-HDMI converter on M2 Pro MacBook
>
> The comment is misleading, "t6000-atcphy-dp-only" would be for M1
> Pro/Max Macbooks. M2 Pro/Max Macbooks use the same design so the
> corresponding "apple,t6020-atcphy-dp-only" compatible is missing.
> I'm not sure this is the correct design though as the HW block is
> identical to "apple,t6000-atcphy".
> I think it might be better to have either the DRM KMS driver or a
> custom DP->HDMI drm_bridge switch the mode to DP-only.
> Or atcphy could initialize itself to DP-only based on the available
> ports.

Doesn't sound like this should be a different compatible. There's a
'phy-mode' property or you can define the mode in the 'phys' cells for
the DP controller.

Rob