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SubjectRe: [PATCH v2 1/5] usb: gadget: Add remote wakeup capable flag
On Sat, Jan 21, 2023 at 02:02:36AM +0000, Thinh Nguyen wrote:
> On Fri, Jan 20, 2023, Alan Stern wrote:
> > A UDC design might have multiple versions, some supporting remote wakeup
> > and others not. But drivers generally use a single static
> > usb_gadget_ops structure, and they don't modify it at runtime to account
> > for hardware differences. So if a single driver controls those multiple
> > versions, you can't rely on the presence of gadget->ops->wakeup to
> > indicate whether there actually is hardware remote wakeup support.
> >
> > Ideally, the usb_gadget structure should have a wakeup_capable flag
> > which the UDC driver would set appropriately (probably during its probe
> > routine).
> >
>
> I was thinking that it can be handled by the
> usb_gadget_enable_remote_wakeup() so we can do away with the
> wakeup_capable flag.

usb_gadget_enable_remote_wakeup() gets called when the gadget or
function is suspended, right? But a gadget driver may want to know long
before that whether the UDC supports remote wakeup, in order to set up
its config descriptor correctly.

Alan Stern

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