Re: [PATCH v10 5/5] usb: gadget: f_ecm: Add suspend/resume and remote wakeup support

[Elson Serrao]

On 3/15/2023 2:15 PM, Thinh Nguyen wrote:
> On Wed, Mar 15, 2023, Thinh Nguyen wrote:
> > On Wed, Mar 15, 2023, Elson Roy Serrao wrote:
> > > When host sends a suspend notification to the device, handle
> > > the suspend callbacks in the function driver. Enhanced super
> > > speed devices can support function suspend feature to put the
> > > function in suspend state. Handle function suspend callback.
> > >
> > > Depending on the remote wakeup capability the device can either
> > > trigger a remote wakeup or wait for the host initiated resume to
> > > start data transfer again.
> > >
> > > Signed-off-by: Elson Roy Serrao <quic_eserrao@xxxxxxxxxxx>
> > > ---
> > >   drivers/usb/gadget/function/f_ecm.c   | 77 +++++++++++++++++++++++++++++++++++
> > >   drivers/usb/gadget/function/u_ether.c | 63 ++++++++++++++++++++++++++++
> > >   drivers/usb/gadget/function/u_ether.h |  4 ++
> > >   3 files changed, 144 insertions(+)
> > >
> > > diff --git a/drivers/usb/gadget/function/f_ecm.c b/drivers/usb/gadget/function/f_ecm.c
> > > index a7ab30e..fea07ab 100644
> > > --- a/drivers/usb/gadget/function/f_ecm.c
> > > +++ b/drivers/usb/gadget/function/f_ecm.c
> > > @@ -633,6 +633,8 @@ static void ecm_disable(struct usb_function *f)
> > >   
> > >   	usb_ep_disable(ecm->notify);
> > >   	ecm->notify->desc = NULL;
> > > +	f->func_suspended = false;
> > > +	f->func_wakeup_armed = false;
> > >   }
> > >   
> > >   /*-------------------------------------------------------------------------*/
> > > @@ -885,6 +887,77 @@ static struct usb_function_instance *ecm_alloc_inst(void)
> > >   	return &opts->func_inst;
> > >   }
> > >   
> > > +static void ecm_suspend(struct usb_function *f)
> > > +{
> > > +	struct f_ecm *ecm = func_to_ecm(f);
> > > +	struct usb_composite_dev *cdev = ecm->port.func.config->cdev;
> > > +
> > > +	if (f->func_suspended) {
> > > +		DBG(cdev, "Function already suspended\n");
> > > +		return;
> > > +	}
> > > +
> > > +	DBG(cdev, "ECM Suspend\n");
> > > +
> > > +	gether_suspend(&ecm->port);
> > > +}
> > > +
> > > +static void ecm_resume(struct usb_function *f)
> > > +{
> > > +	struct f_ecm *ecm = func_to_ecm(f);
> > > +	struct usb_composite_dev *cdev = ecm->port.func.config->cdev;
> > > +
> > > +	/*
> > > +	 * If the function is in USB3 Function Suspend state, resume is
> > > +	 * canceled. In this case resume is done by a Function Resume request.
> > > +	 */
> > > +	if (f->func_suspended)
> > > +		return;
> > > +
> > > +	DBG(cdev, "ECM Resume\n");
> > > +
> > > +	gether_resume(&ecm->port);
> > > +}
> > > +
> > > +static int ecm_get_status(struct usb_function *f)
> > > +{
> > > +	struct usb_configuration *c = f->config;
> > > +
> > > +	/* D0 and D1 bit set to 0 if device is not wakeup capable */
> > > +	if (!(USB_CONFIG_ATT_WAKEUP & c->bmAttributes))
> > > +		return 0;
> > > +
> > > +	return (f->func_wakeup_armed ? USB_INTRF_STAT_FUNC_RW : 0) |
> > > +		USB_INTRF_STAT_FUNC_RW_CAP;
> > > +}
> > > +
> > > +static int ecm_func_suspend(struct usb_function *f, u8 options)
> > > +{
> > > +	struct usb_configuration *c = f->config;
> > > +
> > > +	DBG(c->cdev, "func susp %u cmd\n", options);
> > > +
> > > +	/* Respond with negative errno if request is not supported */
> > > +	if (!(USB_CONFIG_ATT_WAKEUP & c->bmAttributes))
> > > +		return -EINVAL;
> >
> > We only need to return early if the host tries to enable remote wake
> > while the device isn't capable of it:
> >
> > 	wakeup_sel = !!(options & (USB_INTRF_FUNC_SUSPEND_RW >> 8));
> > 	if (wakeup_sel && !(USB_CONFIG_ATT_WAKEUP & c->bmAttributes))
> > 		return -EINVAL;
> >
> > 	f->func_wakeup_armed = wakeup_sel;
>
> Also, I notice that we can't differentiate between ClearFeature() and
> SetFeature() in f->func_suspend(). Perhaps we should handle arming the
> remote wakeup in the composite layer so we can set/clear the remote
> wake. It's common across multiple devices. It's probably better to be
> there.
>
> Thanks,
> Thinh

Yeah agree with that. We check for function_wakeup_armed flag before 
sending remote wakeup in composite.c. So it makes more sense
to set/reset this flag in composite.c itself. I will make that change
and upload v12 along with fixing 'value = 0' removal that we discussed
earlier. Please let me know if that is fine

Thanks
Elson