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

[Elson Serrao]

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 ).

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.
> >    *
> >    * Gadgets have a mostly-portable "gadget driver" implementing device
> >    * functions, handling all usb configurations and interfaces.  Gadget
> > @@ -446,6 +447,7 @@ struct usb_gadget {
> >   	unsigned			lpm_capable:1;
> >   	int				irq;
> >   	int				id_number;
> > +	unsigned			rw_capable:1;
> >   };
> >   #define work_to_gadget(w)	(container_of((w), struct usb_gadget, work))
> >   
> > --
> > 2.7.4