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

[Krishna Kurapati <krishna.kurapati@oss.qualcomm.com>]

On 7/15/2026 4:53 AM, Thinh Nguyen wrote:
> On Mon, Jul 13, 2026, Peter Chen wrote:
>> On 26-07-13 23:41:14, Thinh Nguyen wrote:
>>> On Mon, Jul 13, 2026, Peter Chen wrote:
>>>> On 26-07-13 08:26:59, Krzysztof Kozlowski wrote:
>>>>>>> And Dmitry already said this at v3.
>>>>>>
>>>>>> And I've already responded to his comment in v3:
>>>>>> https://urldefense.com/v3/__https://lore.kernel.org/linux-usb/ahjYwJtiMsm0BcCh@vbox/__;!!A4F2R9G_pg!YksJ0tPtRth9ez8t0GB_WaxH3ynx3ya8M8aFIyKfYpApRC_79Ig93CqE2MKcrGJ6O6t_Dl3RD1zftrnxhdtcfoW7hgep8w$
>>>>>
>>>>> It does not change the fact that type of phy is implied by compatible,
>>>>> thus you do not get a new property.
>>>>>
>>>>>
>>>>
>>>> For USB2 PHY, it has property "phy_type" already, it could extend support
>>>> list to eUSB2 like below, dwc3 qcom glue layer could call of_usb_get_phy_mode
>>>> or re-use dwc3->hsphy_mode depends on where it needs to use.
>>>>
>>>> diff --git a/drivers/usb/phy/of.c b/drivers/usb/phy/of.c
>>>> index 1ab134f45d67..5cbf17d493ad 100644
>>>> --- a/drivers/usb/phy/of.c
>>>> +++ b/drivers/usb/phy/of.c
>>>> @@ -16,6 +16,7 @@ static const char *const usbphy_modes[] = {
>>>>   	[USBPHY_INTERFACE_MODE_ULPI]	= "ulpi",
>>>>   	[USBPHY_INTERFACE_MODE_SERIAL]	= "serial",
>>>>   	[USBPHY_INTERFACE_MODE_HSIC]	= "hsic",
>>>> +	[USBPHY_INTERFACE_MODE_EUSB2]	= "eusb2",
>>>>   };
>>>>
>>>>
>>>
>>> eusb2 uses utmi, so it doesn't fit here as a separate mode.
>>>
>>
>> Hi Thinh
>>
>> Yes, eUSB2 is based on UTMI Parallel mode, but it has dedicated
>> Physical Layer Supplement [1], eg at CH2.4, it lists eUSB2 PHY
>> Features.
>>
>>
>>> To go this route properly, we'd need to introduce a new phy type
>>> attribute in the phy framework, which will be a bigger change that may
>>> impact more than this driver.
>>>
>>
>> It is not at generic PHY framework, it is just for USB PHY dedicated.
>>
>> I do not see big changes, it only needs to change above files and related
>> dt-binding files, and other users may leverage it if the controller
>> has special sequence or settings for eUSB2.
>>
> 
> The usbphy_modes describes the interface between the controller and the
> phy. eusb2 still uses utmi, so adding eusb2 there is sematically
> incorrect. If we introduce the eusb2 mode there, we'd have to audit dwc3
> and every other driver that uses usbphy_modes to handle the new mode
> correctly.

Hi Thinh,

I don't think any existing drivers need to be modified after adding 
this. If anyone wants to use the newly added enum for any eusb2 specific 
purpose, they can do so in a diff change/patch I guess.

Regards,
Krishna,