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Message-ID: <20230317231956.w3kr3zcy44odxdko@synopsys.com>
Date: Fri, 17 Mar 2023 23:20:06 +0000
From: Thinh Nguyen <Thinh.Nguyen@...opsys.com>
To: Elson Serrao <quic_eserrao@...cinc.com>
CC: "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
"quic_wcheng@...cinc.com" <quic_wcheng@...cinc.com>,
"quic_jackp@...cinc.com" <quic_jackp@...cinc.com>
Subject: Re: [PATCH v12 6/6] usb: gadget: f_ecm: Add suspend/resume and remote
wakeup support
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@...cinc.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)) {
+ f->resume(f);
+ f->func_suspended = false;
+ }
+ }
+
if (value < 0) {
ERROR(cdev,
"func_suspend() returned error %d\n",
Also, do we need the f->func_suspended flag? we'd need the remote wakeup
flag for the status, but when do we need f->func_suspended? It seems
like it can be handled within the function driver's scope.
Thanks,
Thinh
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