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

[Peter Chen]

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.


[1] https://usb.org/sites/default/files/eUSB2_1p2_20211217.pdf
-- 

Thanks,
Peter Chen