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Message-ID: <2632a958-2750-c057-2606-c2541efff392@quicinc.com>
Date: Fri, 17 Mar 2023 17:23:28 -0700
From: Elson Serrao <quic_eserrao@...cinc.com>
To: Thinh Nguyen <Thinh.Nguyen@...opsys.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 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.
Please let me know if you see any alternative or better approach here.
Thanks
Elson
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