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SubjectRe: [PATCH v2 1/5] usb: gadget: Add remote wakeup capable flag
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On Fri, Jan 20, 2023, Alan Stern wrote:
> On Sat, Jan 21, 2023 at 12:21:10AM +0000, Thinh Nguyen wrote:
> > The way gadget->rw_capable is named and described, it's a capability
> > flag. That is, its value shouldn't change from the user config. Perhaps
> > we don't need that in the usb_gadget, and we can have something that
> > looks like this:
> >
> > if (gadget->ops->wakeup && (c->bmAttributes & USB_CONFIG_ATT_WAKEUP))
> > usb_gadget_enable_remote_wakeup(g);
> > else
> > usb_gadget_disable_remote_wakeup(g);
> >
> > The setting of the remote wakeup configuration can be tracked internally
> > by the dwc3 driver based on the usb_gadget_enable_remote_wakeup call.
>
> 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.

BR,
Thinh
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