- * Devices on USB hub ports have only one "suspend" state, corresponding
- * to ACPI D2, "may cause the device to lose some context".
- * State transitions include:
- *
- * - suspend, resume ... when the VBUS power link stays live
- * - suspend, disconnect ... VBUS lost
- *
- * Once VBUS drop breaks the circuit, the port it's using has to go through
- * normal re-enumeration procedures, starting with enabling VBUS power.
- * Other than re-initializing the hub (plug/unplug, except for root hubs),
- * Linux (2.6) currently has NO mechanisms to initiate that: no khubd
- * timer, no SRP, no requests through sysfs.
- *
- * If CONFIG_USB_SUSPEND isn't enabled, devices only really suspend when
- * the root hub for their bus goes into global suspend ... so we don't
- * (falsely) update the device power state to say it suspended.
- */
-static int __usb_suspend_device (struct usb_device *udev, int port1)
-{
- int status = 0;
-
- /* caller owns the udev device lock */
- if (port1 < 0)
- return port1;
-
- if (udev->state == USB_STATE_SUSPENDED
- || udev->state == USB_STATE_NOTATTACHED) {
- return 0;
- }
-
- /* all interfaces must already be suspended */
- if (udev->actconfig) {
- int i;
-
- for (i = 0; i < udev->actconfig->desc.bNumInterfaces; i++) {
- struct usb_interface *intf;
-
- intf = udev->actconfig->interface[i];
- if (is_active(intf)) {
- dev_dbg(&intf->dev, "nyet suspended\n");
- return -EBUSY;
- }
- }
- }
-
- /* we only change a device's upstream USB link.
- * root hubs have no upstream USB link.
- */
- if (udev->parent)
- status = hub_port_suspend(hdev_to_hub(udev->parent), port1,
- udev);
-
- if (status == 0)
- udev->dev.power.power_state = PMSG_SUSPEND;
- return status;
-}
-
-#endif
-
-/*
- * usb_suspend_device - suspend a usb device
- * @udev: device that's no longer in active use
- * Context: must be able to sleep; device not locked; pm locks held
- *
- * Suspends a USB device that isn't in active use, conserving power.
- * Devices may wake out of a suspend, if anything important happens,
- * using the remote wakeup mechanism. They may also be taken out of
- * suspend by the host, using usb_resume_device(). It's also routine
- * to disconnect devices while they are suspended.
- *
- * This only affects the USB hardware for a device; its interfaces
- * (and, for hubs, child devices) must already have been suspended.
- *
- * Suspending OTG devices may trigger HNP, if that's been enabled
- * between a pair of dual-role devices. That will change roles, such
- * as from A-Host to A-Peripheral or from B-Host back to B-Peripheral.
- *
- * Returns 0 on success, else negative errno.
- */
-int usb_suspend_device(struct usb_device *udev)
-{
-#ifdef CONFIG_USB_SUSPEND
- int port1, status;
-
- port1 = locktree(udev);
- if (port1 < 0)
- return port1;
-
- status = __usb_suspend_device(udev, port1);
- usb_unlock_device(udev);
- return status;
-#else
- /* NOTE: udev->state unchanged, it's not lying ... */
- udev->dev.power.power_state = PMSG_SUSPEND;
- return 0;
-#endif
-}
-
-/*