Re: [RFC 1/8] dt-bindings: usb: qcom,dwc3: Add bindings to enable runtime

[Krishna Kurapati PSSNV]

On 11/3/2023 8:26 PM, Caleb Connolly wrote:
> On 03/11/2023 05:34, Krishna Kurapati PSSNV wrote:
> > On 11/3/2023 12:10 AM, Caleb Connolly wrote:
> > > > Hi Caleb,
> > > >
> > > >     There are two types of platforms, some use extcon and some use
> > > > role-switch to deliver vbus/id notifications. Extcon targets already
> > > > have this qscratch modifications present today in vbus and id
> > > > handlers. But for role-switch based targets we don't have any way to
> > > > get this notification to dwc3-qcom. In this implementation, I wanted
> > > > to get those notications from core to glue and for this we
> > > > implenented vendor hooks.
> > > >
> > > > The property added has been used to do two things:
> > > >
> > > > 1. Register glue's vendor hooks to core driver
> > > > 2. Do runtime_allow for glue (and by default for core as the dt is
> > > > not flattened)
> > > >
> > > > In case of extcon, we don't want to register vendor hooks as
> > > > notifications are not necessary.
> > >
> > > Could it just be enabled when role_switch is present then?
> > > >
> >
> > So we would register vendor hooks when usb-role-switch is present but
> > don't do runtime allow, and leave that option to user space right ?
> > I think it would work and we can do away with the binding completely.
>
> Can we still enable runtime suspend? Maybe someone else wants to chime
> in here, but I'd guess that it's preferable to have it enabled by
> default, particularly for devices like phones. Or are there side effects
> from this?
> >

AFAIK, I don't see any side effects whether we enable runtime from user 
space or do runtime_allow() here in kernel itself and leave qscratch 
config to vendor hooks.

But leaving it enabled by default, we do this for almost all targets in 
downstream today. So I guess there would be no side effects.

Regards,
Krishna,