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 7/16/2026 4:49 AM, Thinh Nguyen wrote:
> On Wed, Jul 15, 2026, Krishna Kurapati wrote:
>>
>>
>> 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.
>>
> 
> At minimum, dwc3 needs to be reviewed and updated for dwc->hsphy_mode
> check when configuring GUSB2PHYCFG. Regardless, phy type should not be a
> usbphy_modes enum as I noted above.
> 
We can just add the enum for eusb2 in of.c as pointed by Peter in [1], 
read that in dwc3-qcom.c and use it during suspend resume for interrupt 
handling and to modify the DWC3_GUSB2PHYCFG_EUSB2OPMODE bit once we are 
modifying it in core.

[1]: https://lore.kernel.org/all/alhDjZ0gJZq_7G6z@hu-petche-lv.qualcomm.com/

Regards,
Krishna,