Re: [PATCH v2 1/5] usb: gadget: Add remote wakeup capable flag

[Elson Serrao]

On 1/19/2023 5:15 PM, Thinh Nguyen wrote:
> On Thu, Jan 19, 2023, Elson Serrao wrote:
> > On 1/18/2023 5:44 PM, Thinh Nguyen wrote:
> > > On Tue, Jan 17, 2023, Elson Roy Serrao wrote:
> > > > Add a flag to indicate whether the gadget is capable
> > > > of sending remote wakeup to the host.
> > > >
> > > > Signed-off-by: Elson Roy Serrao <quic_eserrao@xxxxxxxxxxx>
> > > > ---
> > > >    drivers/usb/gadget/composite.c | 3 +++
> > > >    include/linux/usb/gadget.h     | 2 ++
> > > >    2 files changed, 5 insertions(+)
> > > >
> > > > diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
> > > > index 403563c..b83963a 100644
> > > > --- a/drivers/usb/gadget/composite.c
> > > > +++ b/drivers/usb/gadget/composite.c
> > > > @@ -965,6 +965,9 @@ static int set_config(struct usb_composite_dev *cdev,
> > > >    	else
> > > >    		usb_gadget_clear_selfpowered(gadget);
> > > > +	if (USB_CONFIG_ATT_WAKEUP & c->bmAttributes)
> > > > +		gadget->rw_capable = 1;
> > >
> > > Some device may not support remote wakeup. gadget->rw_capable should be
> > > set and reported by the UDC. May need a gadget ops to enable remote
> > > wakeup here.
> > >
> > > Thanks,
> > > Thinh
> > Not exactly clear on which parameter in UDC decides whether a device
> > supports remote wakeup. Here I have this flag just to indicate whether the
> > connected device is rw capable based on the bmAttributes populated in the
> > config descriptor. If the UDC doesnt have a callback for remote wakeup we
> > have that check when calling the gadget op in udc/core.c (have added a
> > similar check in usb_func_wakeup() also ).
>
> That flag describes the gadget's capability, not the device
> configuration. However, it's being used as a configuration flag.
>
> Thanks,
> Thinh

Thank you for the clarification. Please let me know if below approach 
where we consider both gadget's capability and device configuration fine?

if (gadget->ops->wakeup || gadget->ops->func_wakeup)
   gadget->rw_capable = USB_CONFIG_ATT_WAKEUP & c->bmAttributes ? 1: 0;

Thanks
Elson
> > int usb_gadget_wakeup(struct usb_gadget *gadget)
> > {
> > 	int ret = 0;
> >
> > 	if (!gadget->ops->wakeup) {
> > 		ret = -EOPNOTSUPP;
> > 		goto out;
> >
> > Thanks
> > Elson
> >
> > > > +
> > > >    	usb_gadget_vbus_draw(gadget, power);
> > > >    	if (result >= 0 && cdev->delayed_status)
> > > >    		result = USB_GADGET_DELAYED_STATUS;
> > > > diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h
> > > > index dc3092c..15785f8 100644
> > > > --- a/include/linux/usb/gadget.h
> > > > +++ b/include/linux/usb/gadget.h
> > > > @@ -385,6 +385,7 @@ struct usb_gadget_ops {
> > > >     *	indicates that it supports LPM as per the LPM ECN & errata.
> > > >     * @irq: the interrupt number for device controller.
> > > >     * @id_number: a unique ID number for ensuring that gadget names are distinct
> > > > + * @rw_capable: True if the gadget is capable of sending remote wakeup.
> > > >     *