Re: [PATCH v4 1/2] dt-bindings: qcom,snps-dwc3: Add property indicating presence of eUSB2 phy

[Krzysztof Kozlowski <krzk@kernel.org>]

On 10/07/2026 23:02, Thinh Nguyen wrote:
> On Fri, Jul 10, 2026, Krzysztof Kozlowski wrote:
>> On 10/07/2026 09:16, Krzysztof Kozlowski wrote:
>>> On Fri, Jul 10, 2026 at 01:52:45AM +0000, Thinh Nguyen wrote:
>>>> On Thu, Jul 09, 2026, Dmitry Baryshkov wrote:
>>>>> On Thu, Jul 09, 2026 at 02:22:36PM +0530, Krishna Kurapati wrote:
>>>>>> Add property "qcom,has-eusb2-phy" to indicate whether the SoC has eUSB2 phy
>>>>>> or not. This is used to modify dp/dm interrupts during host mode suspend.
>>>>>>
>>>>>> Signed-off-by: Krishna Kurapati <krishna.kurapati@oss.qualcomm.com>
>>>>>> ---
>>>>>>  Documentation/devicetree/bindings/usb/qcom,snps-dwc3.yaml | 7 +++++++
>>>>>>  1 file changed, 7 insertions(+)
>>>>>>
>>>>>> diff --git a/Documentation/devicetree/bindings/usb/qcom,snps-dwc3.yaml b/Documentation/devicetree/bindings/usb/qcom,snps-dwc3.yaml
>>>>>> index 8201656b41ed..0c6a839be82f 100644
>>>>>> --- a/Documentation/devicetree/bindings/usb/qcom,snps-dwc3.yaml
>>>>>> +++ b/Documentation/devicetree/bindings/usb/qcom,snps-dwc3.yaml
>>>>>> @@ -152,6 +152,13 @@ properties:
>>>>>>        HS/FS/LS modes are supported.
>>>>>>      type: boolean
>>>>>>  
>>>>>> +  qcom,has-eusb2-phy:
>>>>>> +    description:
>>>>>> +      If present, it indicates that the controller is working with eUSB2
>>>>>> +      phy. This property is used to modify dp/dm interrupt configurations
>>>>>> +      while entering suspend.
>>>>>> +    type: boolean
>>>>>
>>>>> I still have exactly the same concern. This information is already
>>>>> present in the DT.
>>>>>
>>>>
>>>> Could you clarify what you mean by "this information is already present
>>>> in the DT"? Are you suggesting we use the dwc3 node's compatible string
>>>> to infer the phy type?
>>>>
>>>> The dwc3 glue compatible describes the controller, not the phy. They are
>>>> separate IP blocks. A board variant could reuse the same dwc3 compatible
>>>> with a different phy attached, making that inference silently wrong.
>>>>
>>>> The phy type is described somewhere else in the DT (in the phy node
>>>> itself), referenced via the phy's phandle on the dwc3 core child node.
>>>> We could walk that phandle and check whether the phy node's compatible
>>>> contains "eusb2". However, that relies on a naming convention that isn't
>>>> enforced anywhere. All current eusb2 phy compatibles happen to follow it
>>>> (qcom,sm8550-snps-eusb2-phy, qcom,sm8750-m31-eusb2-phy,
>>>> samsung,exynos2200-eusb2-phy, etc.), but a future phy driver could break
>>>
>>> You have a fixed/finite list of phys which needs something special, so
>>> that information as Dmitry said is in DT already.
> 
> Are you referring to a fixed list of eusb2 phy compatibles, or a fixed
> list of dwc3 node compatibles?

The phys.

> 
> Either way, the list is not fixed. New eusb2 SoC variants are added
> regularly, and there are already 12 eusb2 phy compatible strings in the

It is fixed. You have 12 compatible strings, so it is strictly defined.

> DT bindings but only 3 in the PHY driver of_match tables, they don't
> land at the same time. As for what information is already in DT, I've
> addressed this above and in my earlier response.
> 
>>>
>>> Anyway, the commit msg and property field have insufficient description
>>> of actual hardware problem being represented by this property, so it
>>> looks way too much as SW policy.
> 
> That's fair feedback to raise with Krishna.
> 
>>
>>
>> And Dmitry already said this at v3.
> 
> And I've already responded to his comment in v3:
> https://lore.kernel.org/linux-usb/ahjYwJtiMsm0BcCh@vbox/

It does not change the fact that type of phy is implied by compatible,
thus you do not get a new property.


Best regards,
Krzysztof