linux-kernel - Re: [PATCH v2 1/2] dt-bindings: usb: ti,hd3ss3220: Add support for VBUS based on ID state

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Message-ID: <20251009131543.GA379737-robh@kernel.org>
Date: Thu, 9 Oct 2025 08:15:43 -0500
From: Rob Herring <robh@...nel.org>
To: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
Cc: Krishna Kurapati <krishna.kurapati@....qualcomm.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
	Liam Girdwood <lgirdwood@...il.com>,
	Mark Brown <broonie@...nel.org>,
	Biju Das <biju.das.jz@...renesas.com>, linux-usb@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] dt-bindings: usb: ti,hd3ss3220: Add support for
 VBUS based on ID state

On Wed, Oct 08, 2025 at 09:31:59PM +0300, Dmitry Baryshkov wrote:
> On Wed, Oct 08, 2025 at 11:27:49PM +0530, Krishna Kurapati wrote:
> > Update the bindings to support reading ID state and VBUS, as per the
> > HD3SS3220 data sheet. The ID pin is kept high if VBUS is not at VSafe0V and
> > asserted low once VBUS is at VSafe0V, enforcing the Type-C requirement that
> > VBUS must be at VSafe0V before re-enabling VBUS.
> > 
> > Add id-gpios property to describe the input gpio for USB ID pin and vbus-
> > supply property to describe the regulator for USB VBUS.
> > 
> > Signed-off-by: Krishna Kurapati <krishna.kurapati@....qualcomm.com>
> > ---
> >  .../devicetree/bindings/usb/ti,hd3ss3220.yaml       | 13 +++++++++++++
> >  1 file changed, 13 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/usb/ti,hd3ss3220.yaml b/Documentation/devicetree/bindings/usb/ti,hd3ss3220.yaml
> > index bec1c8047bc0..c869eece39a7 100644
> > --- a/Documentation/devicetree/bindings/usb/ti,hd3ss3220.yaml
> > +++ b/Documentation/devicetree/bindings/usb/ti,hd3ss3220.yaml
> > @@ -25,6 +25,19 @@ properties:
> >    interrupts:
> >      maxItems: 1
> >  
> > +  id-gpios:
> > +    description:
> > +      An input gpio for USB ID pin. Upon detecting a UFP device, HD3SS3220
> > +      will keep ID pin high if VBUS is not at VSafe0V. Once VBUS is at VSafe0V,
> > +      the HD3SS3220 will assert ID pin low. This is done to enforce Type-C
> > +      requirement that VBUS must be at VSafe0V before re-enabling VBUS.
> > +
> 
> Stray empty line?
> 
> > +    maxItems: 1
> > +
> > +  vbus-supply:
> > +    description: A phandle to the regulator for USB VBUS if needed when host
> > +      mode or dual role mode is supported.
> 
> Why are we adding the property here while we can use the vbus-supply of
> the usb-c-connector?

Normally, that's my question on both of these, too. However, it does 
look like both are connected to the chip. There's VBUS_DET which is 
connected to Vbus (thru a 900k resistor). So having these here does look 
like accurate representation of the h/w. The commit message should make 
this more clear. Honestly, that's really the only part I care about. 
How it works is not so important. 

Rob