RE: Remote wakeup timing

[Chen Peter-B29397 <B29397@xxxxxxxxxxxxx>]

> 
> > > A better approach might be to have ehci_bus_resume check the port
> > > statuses before turning on CMD_RUN, and re-suspend any enabled port
> > > that isn't already suspended.  Then when the controller starts
> sending
> > > SOF packets, the host shouldn't think the device had disconnected.
> > > Would that solve your problem?
> 
> What about this patch?
> 
Good patch, Alan. Only one thing is that it needs a delay between
re-suspend, and send resume again. (Sorry, I can't find the detail
delay time between suspend and resume signal at usb2.0 spec).

I will test this patch, and give you a response.


> Alan Stern
> 
> 
> 
>  drivers/usb/host/ehci-hub.c |   63
> +++++++++++++++++++++++++++++++++++++++++---
>  1 file changed, 59 insertions(+), 4 deletions(-)
> 
> Index: usb-3.4/drivers/usb/host/ehci-hub.c
> ===================================================================
> --- usb-3.4.orig/drivers/usb/host/ehci-hub.c
> +++ usb-3.4/drivers/usb/host/ehci-hub.c
> @@ -329,6 +329,59 @@ static int ehci_bus_suspend (struct usb_
>  }
> 
> 
> +static void ehci_resuspend_ports(struct ehci_hcd *ehci)
> +{
> +	u32			temp;
> +	int			i;
> +	unsigned long		resuspend_needed = 0;
> +
> +	/*
> +	 * If a remote wakeup request was received, the controller will
> +	 * already have begun resume signalling on that port.  Some buggy
> +	 * controllers (e.g., Synopsys) automatically turn off the resume
> +	 * signal after 20 ms, leaving the port active and using high-speed
> +	 * signalling.  But since CMD_RUN has been turned off, the device
> +	 * will not have received any SOF packets, so it will have gone
> +	 * back into suspend, using full-speed signalling.  As a result,
> +	 * when the controller starts sending SOF packets again, it will
> +	 * think the device has disconnected.
> +	 *
> +	 * To avoid this problem, check to see if any enabled ports are
> +	 * resumed or resuming, and force them back into suspend before
> +	 * turning on CMD_RUN.
> +	 */
> +	i = HCS_N_PORTS(ehci->hcs_params);
> +	while (i--) {
> +		temp = ehci_readl(ehci, &ehci->regs->port_status[i]);
> +		temp &= ~(PORT_RWC_BITS | PORT_WAKE_BITS);
> +		if ((temp & PORT_PE) && (!(temp & PORT_SUSPEND) ||
> +				(temp & PORT_RESUME))) {
> +			__set_bit(i, &resuspend_needed);
> +			temp &= ~PORT_RESUME;
> +			ehci_writel(ehci, temp, &ehci->regs->port_status[i]);
> +		}
> +	}
> +
> +	/* Give the port time to leave suspend, then resuspend it */
> +	if (resuspend_needed) {
> +		spin_unlock_irq(&ehci->lock);
> +		msleep(3);
> +		spin_lock_irq(&ehci->lock);
> +
> +		i = HCS_N_PORTS(ehci->hcs_params);
> +		while (i--) {
> +			if (test_bit(i, &resuspend_needed)) {
> +				temp = ehci_readl(ehci,
> +						&ehci->regs->port_status[i]);
> +				temp &= ~PORT_RWC_BITS;
> +				temp |= PORT_SUSPEND;
> +				ehci_writel(ehci, temp,
> +						&ehci->regs->port_status[i]);
> +			}
> +		}
> +	}
> +}
> +
>  /* caller has locked the root hub, and should reset/reinit on error */
>  static int ehci_bus_resume (struct usb_hcd *hcd)
>  {
> @@ -373,10 +426,6 @@ static int ehci_bus_resume (struct usb_h
>  	ehci_writel(ehci, ehci->periodic_dma, &ehci->regs->frame_list);
>  	ehci_writel(ehci, (u32) ehci->async->qh_dma, &ehci->regs-
> >async_next);
> 
> -	/* restore CMD_RUN, framelist size, and irq threshold */
> -	ehci_writel(ehci, ehci->command, &ehci->regs->command);
> -	ehci->rh_state = EHCI_RH_RUNNING;
> -
>  	/* Some controller/firmware combinations need a delay during which
>  	 * they set up the port statuses.  See Bugzilla #8190. */
>  	spin_unlock_irq(&ehci->lock);
> @@ -402,6 +451,12 @@ static int ehci_bus_resume (struct usb_h
>  		spin_lock_irq(&ehci->lock);
>  	}
> 
> +	ehci_resuspend_ports(ehci);
> +
> +	/* restore CMD_RUN, framelist size, and irq threshold */
> +	ehci_writel(ehci, ehci->command, &ehci->regs->command);
> +	ehci->rh_state = EHCI_RH_RUNNING;
> +
>  	/* manually resume the ports we suspended during bus_suspend() */
>  	i = HCS_N_PORTS (ehci->hcs_params);
>  	while (i--) {
> 


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