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: <2a088c8f-5555-490e-a70d-308a876924ca@oss.qualcomm.com>
Date: Mon, 13 Oct 2025 06:47:04 +0530
From: Krishna Kurapati PSSNV <krishna.kurapati@....qualcomm.com>
To: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>,
        Rob Herring <robh@...nel.org>
Cc: 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 10/9/2025 8:08 PM, Dmitry Baryshkov wrote:
> On Thu, Oct 09, 2025 at 08:15:43AM -0500, Rob Herring wrote:
>> 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.
> 
> The VBUS_DET pin is used by the controller to detect the VBUS provided
> by the USB-C partner and to identify when it's safe to turn on the
> device's VBUS supply. I think this still fits into the description of
> the connector's vbus-supply.
> 


Hi Dmitry,

  In case we put the vbus supply in usb-c-connector node, is there any 
way we can get its phandle reference in hd3 driver given that the 
connector node is not a child or parent of port controller node.

Regards,
Krishna,