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

[Peter Chen]

On 26-07-14 23:23:01, Thinh Nguyen wrote:
> On Mon, Jul 13, 2026, Peter Chen wrote:
> > 
> > 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.
> 
> That said, I have no objection to adding a new phy type for eusb2. I
> just want to note it is a bigger change relative to adding a boolean
> property to the DT binding.
> 

Hi Thinh,

Only the new user for adding phy_type="eusb2" at dts needs to check the
controller logic, and this is what the user needs to do that check the
new added device tree property logic at the driver.

So, it will not affect current user for phy_type, and I checked the dwc3
core, it does not need to change code for new phy type.

Currently, it is only benefit for qcom platform, but eusb2 (uesb2v2 later)
is the common USB2 mode, other users may leverage for this new phy type.

Krzysztof and Dmitry, do you agree we use existed device tree property
for this feature? 

-- 

Thanks,
Peter Chen