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 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?

> +
> +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)?

Thanks,
Thinh

> +		if (!f->func_suspended) {
> +			ecm_suspend(f);
> +			f->func_suspended = true;
> +		}
> +	} else {
> +		if (f->func_suspended) {
> +			f->func_suspended = false;
> +			ecm_resume(f);
> +		}
> +	}
> +
> +	return 0;
> +}
> +