Re: [PATCH v12 6/6] usb: gadget: f_ecm: Add suspend/resume and remote wakeup support

[Thinh Nguyen <Thinh.Nguyen@synopsys.com>]

On Thu, Mar 23, 2023, Elson Serrao wrote:
> 
> 
> On 3/20/2023 10:42 AM, Elson Serrao wrote:
> > 
> > 
> > On 3/17/2023 7:26 PM, Thinh Nguyen wrote:
> > > On Fri, Mar 17, 2023, Elson Serrao wrote:
> > > > 
> > > > 
> > > > On 3/17/2023 4:20 PM, Thinh Nguyen wrote:
> > > > > On Fri, Mar 17, 2023, Thinh Nguyen wrote:
> > > > > > On Fri, Mar 17, 2023, Elson Serrao wrote:
> > > > > > > 
> > > > > > > 
> > > > > > > On 3/16/2023 5:11 PM, Thinh Nguyen wrote:
> > > > > > > > On Thu, Mar 16, 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@quicinc.com>
> > > > > > > > > ---
> > > > > > > > >     drivers/usb/gadget/function/f_ecm.c   |
> > > > > > > > > 71 +++++++++++++++++++++++++++++++++++
> > > > > > > > >     drivers/usb/gadget/function/u_ether.c |
> > > > > > > > > 63 +++++++++++++++++++++++++++++++
> > > > > > > > >     drivers/usb/gadget/function/u_ether.h |  4 ++
> > > > > > > > >     3 files changed, 138 insertions(+)
> > > > > > > > > 
> > > > > > > > > diff --git
> > > > > > > > > a/drivers/usb/gadget/function/f_ecm.c
> > > > > > > > > b/drivers/usb/gadget/function/f_ecm.c
> > > > > > > > > index a7ab30e..c43cd557 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 +887,71 @@ 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;
> > > > > > > > > +}
> > > > > > > > 
> > > > > > > > Why do we need to implement ecm_get_status if
> > > > > > > > it's already handled in
> > > > > > > > composite.c now?
> > > > > > > > 
> > > > > > > 
> > > > > > > Yes this can be removed now. Will modify accordingly.
> > > > > > > > > +
> > > > > > > > > +static int ecm_func_suspend(struct usb_function *f, u8 options)
> > > > > > > > > +{
> > > > > > > > > +    struct usb_composite_dev *cdev = f->config->cdev;
> > > > > > > > > +
> > > > > > > > > +    DBG(cdev, "func susp %u cmd\n", options);
> > > > > > > > > +
> > > > > > > > > +    if (options & (USB_INTRF_FUNC_SUSPEND_LP >> 8)) {
> > > > > > > > 
> > > > > > > > This feature selector doesn't indicate whether it's SetFeature or
> > > > > > > > ClearFeature request. ecm_func_suspend is supposed to be for
> > > > > > > > SetFeature(suspend) only. Perhaps we may have to
> > > > > > > > define func_resume()
> > > > > > > > for ClearFeature(suspend)?
> > > > > > > > 
> > > > > > 
> > > > > > > Host uses the same feature selector FUNCTION_SUSPEND
> > > > > > > for function suspend
> > > > > > > and function resume and func_suspend() callback can be used to
> > > > > > > handle both the cases ? The distinction comes whether it is a
> > > > > > 
> > > > > > How do you plan to handle that? Pass this info in some unused/reserved
> > > > > > bit of the "options" argument? Introduce a new parameter to the
> > > > > > func_suspend()?
> > > > > > 
> > > > > > If that's the case, then you need to update the document on
> > > > > > func_suspend() to also support ClearFeature(suspend). Right now it's
> > > > > > documented for SetFeature only. Also, make sure that other existing
> > > > > > function drivers will not break because of the change of the
> > > > > > func_suspend behavior.
> > > > > > 
> > > > > > > SetFeature(FUNCTION_SUSPEND) or
> > > > > > > ClearFeature(FUNCTION_SUSPEND) which can be
> > > > > > > easily done in the func_suspend callback itself. We
> > > > > > > can add another callback
> > > > > > > func_resume specific to
> > > > > > > ClearFeature(FUNCTION_SUSPEND) but wont that be
> > > > > > > redundant and more callback handling on function
> > > > > > > driver/composite side as
> > > > > > > well? Please let me know your opinion.
> > > > > > > 
> > > > > > 
> > > > > > We actually didn't properly define func_suspend and its
> > > > > > counter part. It
> > > > > > seems cleaner to me to introduce func_resume as it seems
> > > > > > more intuitive
> > > > > > and easier to read. Let me know how you plan to use func_suspend() for
> > > > > > both cases.
> > > > > > 
> > > > > 
> > > > > How about we handle function suspend resume in composite also? I mean
> > > > > something like this:
> > > > > 
> > > > > diff --git a/drivers/usb/gadget/composite.c
> > > > > b/drivers/usb/gadget/composite.c
> > > > > index 36add1879ed2..79dc055eb5f7 100644
> > > > > --- a/drivers/usb/gadget/composite.c
> > > > > +++ b/drivers/usb/gadget/composite.c
> > > > > @@ -1948,9 +1948,18 @@ composite_setup(struct usb_gadget
> > > > > *gadget, const struct usb_ctrlrequest *ctrl)
> > > > >            f = cdev->config->interface[intf];
> > > > >            if (!f)
> > > > >                break;
> > > > > -        status = f->get_status ? f->get_status(f) : 0;
> > > > > -        if (status < 0)
> > > > > -            break;
> > > > > +
> > > > > +        if (f->get_status) {
> > > > > +            status = f->get_status(f);
> > > > > +            if (status < 0)
> > > > > +                break;
> > > > > +        } else {
> > > > > +            if (f->config->bmAttributes & USB_CONFIG_ATT_WAKEUP) {
> > > > > +                status |= USB_INTRF_STAT_FUNC_RW_CAP;
> > > > > +                if (f->func_wakeup_armed)
> > > > > +                    status |= USB_INTRF_STAT_FUNC_RW;
> > > > > +            }
> > > > > +        }
> > > > >            put_unaligned_le16(status & 0x0000ffff, req->buf);
> > > > >            break;
> > > > >        /*
> > > > > @@ -1971,9 +1980,28 @@ composite_setup(struct usb_gadget
> > > > > *gadget, const struct usb_ctrlrequest *ctrl)
> > > > >                f = cdev->config->interface[intf];
> > > > >                if (!f)
> > > > >                    break;
> > > > > +            if (w_index & USB_INTRF_FUNC_SUSPEND_RW) {
> > > > > +                if (!(f->config->bmAttributes &
> > > > > USB_CONFIG_ATT_WAKEUP))
> > > > > +                    break;
> > > > > +
> > > > > +                f->func_wakeup_armed = (ctrl->bRequest ==
> > > > > USB_REQ_SET_FEATURE);
> > > > > +            }
> > > > > +
> > > > >                value = 0;
> > > > > -            if (f->func_suspend)
> > > > > +            if (f->func_suspend) {
> > > > >                    value = f->func_suspend(f, w_index >> 8);
> > > > > +            } else if (w_index & USB_INTRF_FUNC_SUSPEND_LP) {
> > > > > +                if (f->suspend && && !f->func_suspended &&
> > > > > +                    ctrl->bRequest == USB_REQ_SET_FEATURE)) {
> > > > > +                    f->suspend(f);
> > > > > +                    f->func_suspended = true;
> > > > > +                } else if (f->resume && f->func_suspended &&
> > > > > +                       ctrl->bRequest ==
> > > > > USB_REQ_CLEAR_FEATURE_FEATURE)) {
> 
> Linux based hosts, dont use ClearFeature(FUNCTION_SUSPEND) for function
> resume. They use SetFeature(FUNCTION_SUSPEND) itself but with Bit(0) i.e
> USB_INTRF_FUNC_SUSPEND_LP reset. So we may not be able to distinguish based
> on SET_FEATURE and CLEAR_FEATURE packets for function suspend and function
> resume. Instead we can generalize (w_index & USB_INTRF_FUNC_SUSPEND_LP) for
> function suspend and all other cases for function resume.
> 
> if (f->func_suspend) {
> 		value = f->func_suspend(f, w_index >> 8);
> } else if (w_index & USB_INTRF_FUNC_SUSPEND_LP) {
> 		if (f->suspend && !f->func_suspended) {
> 				f->suspend(f);
> 				f->func_suspended = true;
> 		}
> } else {
> 		if (f->resume && f->func_suspended) {
> 				f->resume(f);
> 				f->func_suspended = false;
> 		}
> }
> 
> 

Ah.. right. That's possible also. Then can we check for both cases?
Something like this:

@ -1994,8 +2003,34 @@ composite_setup(struct usb_gadget *gadget, const struct usb_ctrlrequest *ctrl)
                        if (!f)
                                break;
                        value = 0;
-                       if (f->func_suspend)
+                       if (f->func_suspend) {
                                value = f->func_suspend(f, w_index >> 8);
+                       } else if (ctrl->bRequest == USB_REQ_SET_FEATURE) {
+                               if (!(f->config->bmAttributes & USB_CONFIG_ATT_WAKEUP) &&
+                                   (w_index & USB_INTRF_FUNC_SUSPEND_RW))
+                                               break;
+
+                               f->func_wakeup_armed = !!(w_index & USB_INTRF_FUNC_SUSPEND_RW);
+
+                               if ((w_index & USB_INTRF_FUNC_SUSPEND_LP) &&
+                                   f->suspend && !f->func_suspended) {
+                                       f->suspend(f);
+                                       f->func_suspended = true;
+                               } else if (f->resume && f->func_suspended) {
+                                       f->resume(f);
+                                       f->func_suspended = false;
+                               }
+                       } else if (ctrl->bRequest == USB_REQ_CLEAR_FEATURE_FEATURE)) {
+                               if (w_index & USB_INTRF_FUNC_SUSPEND_RW)
+                                       f->func_wakeup_armed = false;
+
+                               if ((w_index & USB_INTRF_FUNC_SUSPEND_LP) &&
+                                   f->resume && f->func_suspended) {
+                                       f->resume(f);
+                                       f->func_suspended = false;
+                               }
+                       }
+
                        if (value < 0) {
                                ERROR(cdev,
                                      "func_suspend() returned error %d\n",


Thanks,
Thinh