On Fri, 13 Oct 2017, Daniel Drake wrote:
> When going into S3 suspend, the Acer TravelMate P648-M and P648-G3
> laptops immediately wake up 3-4 seconds later for no obvious reason.
>
> Unbinding the integrated Huawei 4G LTE modem before suspend avoids
> the issue, even though we are not using the modem at all (checked
> from rescue.target/runlevel1). The problem also occurs when the option
> and cdc-ether modem drivers aren't loaded; it reproduces just with the
> base usb driver. Under Windows the system can suspend fine.
>
> Seeking a better fix, we've tried a lot of things, including:
> - Check that the device's power/wakeup is disabled
> - Check that remote wakeup is off at the USB level
> - All the quirks in drivers/usb/core/quirks.c e.g. USB_QUIRK_RESET_RESUME,
> USB_QUIRK_RESET, USB_QUIRK_IGNORE_REMOTE_WAKEUP, USB_QUIRK_NO_LPM.
>
> but none of that makes any difference.
>
> There are no errors in the logs showing any suspend/resume-related issues.
> When the system wakes up due to the modem, log-wise it appears to be a
> normal resume.
>
> Introduce a quirk to disable the port during suspend when the modem is
> detected.
> diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
> index eb87a259d55c..7c048afc9bfd 100644
> --- a/drivers/usb/core/driver.c
> +++ b/drivers/usb/core/driver.c
> @@ -1461,6 +1461,7 @@ static void choose_wakeup(struct usb_device *udev, pm_message_t msg)
> int usb_suspend(struct device *dev, pm_message_t msg)
> {
> struct usb_device *udev = to_usb_device(dev);
> + int r;
>
> unbind_no_pm_drivers_interfaces(udev);
>
> @@ -1469,7 +1470,14 @@ int usb_suspend(struct device *dev, pm_message_t msg)
> * so we may still need to unbind and rebind upon resume
> */
> choose_wakeup(udev, msg);
> - return usb_suspend_both(udev, msg);
> + r = usb_suspend_both(udev, msg);
> + if (r)
> + return r;
> +
> + if (udev->quirks & USB_QUIRK_DISCONNECT_SUSPEND)
> + r = usb_port_disable(udev);
> +
> + return r;
Here it's probably best to ignore the return value. Even if
usb_port_disable failed, you want the system suspend to move forward --
even if the system spontaneously wakes up a second later.
> }
>
> /* The device lock is held by the PM core */
> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
> index b5c733613823..9662eaa9c44d 100644
> --- a/drivers/usb/core/hub.c
> +++ b/drivers/usb/core/hub.c
> @@ -4180,6 +4180,19 @@ static int hub_port_disable(struct usb_hub *hub, int port1, int set_state)
> return ret;
> }
>
> +/*
> + * usb_port_disable - disable a usb device's upstream port
> + * @udev: device to disable
> + * Context: must be able to sleep; device not locked; pm locks held
Actually the device _is_ locked when this routine gets called. And the
PM locks are not held.
> + *
> + * Disables a USB device that isn't in active use.
> + */
> +int usb_port_disable(struct usb_device *udev)
> +{
> + struct usb_hub *hub = usb_hub_to_struct_hub(udev->parent);
> +
> + return hub_port_disable(hub, udev->portnum, 1);
> +}
You probably want the last argument to be 0, not 1. The 1 will cause
the device to be marked as disconnected, so when the system wakes up it
will think that a new device has been plugged in rather than the old
device having been attached all along.
Alan Stern
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