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Message-ID: <20230318022558.z5v5ktfus5yt4atc@synopsys.com>
Date: Sat, 18 Mar 2023 02:26:13 +0000
From: Thinh Nguyen <Thinh.Nguyen@...opsys.com>
To: Elson Serrao <quic_eserrao@...cinc.com>
CC: Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
"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, 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@...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",
> >
> At individual function driver level there is no need to differentiate
> between suspend() and func_suspend() APIs, as both are intended to put the
> function in suspend state. So your idea/implementation above makes it much
> more clearer. Let composite also handle this and call either f->suspend() or
> f->resume() callback based on the setup packet received. Thank you for this
> suggestion.
>
> >
> > 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.
>
> f->func_suspended flag I had added for below purposes
>
> 1.) Function drivers should know the right wakeup() op to be called.
> That is if they are in FUNC_SUSPEND then call usb_func_wakeup() and if they
> are in device suspend then call usb_gadget_wakeup(). (we can use
> f->func_wakeup_armed flag for this purpose as well)
>
> 2.) If a function is in USB3 FUNCTION_SUSPEND state then it shouldn't allow
> f->resume() called through composite_resume() as the exit from
> FUNCTION_SUSPEND state is via ClearFeature(FUNCTION_SUSPEND).
>
> So we need a way to tell function drivers if they are in USB3
> FUNCTION_SUSPEND state OR device suspend.
Ok. So do you plan to update composite_resume to check that? Perhaps
document this expected behavior also?
>
> Please let me know if you see any alternative or better approach here.
>
If we have a use for it in composite.c, then it should be made
available. Otherwise it should only exist in the function driver (ie. in
f_ecm structure).
Thanks,
Thinh
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