USB: implement usb_enable_autosuspend
This patch (as1326) adds usb_enable_autosuspend() and usb_disable_autosuspend() routines for use by drivers. If a driver knows that its device can handle suspends and resumes correctly, it can enable autosuspend all by itself. This is equivalent to the user writing "auto" to the device's power/level attribute. The implementation differs slightly from what it used to be. Now autosuspend is disabled simply by doing usb_autoresume_device() (to increment the usage counter) and enabled by doing usb_autosuspend_device() (to decrement the usage counter). The set_level() attribute method is updated to use the new routines, and the USB Power-Management documentation is updated. The patch adds a usb_enable_autosuspend() call to the hub driver's probe routine, allowing the special-case code for hubs in quirks.c to be removed. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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@ -229,6 +229,11 @@ necessary operations by hand or add them to a udev script. You can
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also change the idle-delay time; 2 seconds is not the best choice for
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every device.
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If a driver knows that its device has proper suspend/resume support,
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it can enable autosuspend all by itself. For example, the video
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driver for a laptop's webcam might do this, since these devices are
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rarely used and so should normally be autosuspended.
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Sometimes it turns out that even when a device does work okay with
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autosuspend there are still problems. For example, there are
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experimental patches adding autosuspend support to the usbhid driver,
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@ -384,6 +389,19 @@ autosuspend, there's no delay for an autoresume.
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Other parts of the driver interface
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-----------------------------------
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Drivers can enable autosuspend for their devices by calling
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usb_enable_autosuspend(struct usb_device *udev);
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in their probe() routine, if they know that the device is capable of
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suspending and resuming correctly. This is exactly equivalent to
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writing "auto" to the device's power/level attribute. Likewise,
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drivers can disable autosuspend by calling
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usb_disable_autosuspend(struct usb_device *udev);
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This is exactly the same as writing "on" to the power/level attribute.
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Sometimes a driver needs to make sure that remote wakeup is enabled
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during autosuspend. For example, there's not much point
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autosuspending a keyboard if the user can't cause the keyboard to do a
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@ -1415,6 +1415,48 @@ static int usb_resume_both(struct usb_device *udev, pm_message_t msg)
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#ifdef CONFIG_USB_SUSPEND
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/**
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* usb_enable_autosuspend - allow a USB device to be autosuspended
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* @udev: the USB device which may be autosuspended
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*
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* This routine allows @udev to be autosuspended. An autosuspend won't
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* take place until the autosuspend_delay has elapsed and all the other
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* necessary conditions are satisfied.
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*
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* The caller must hold @udev's device lock.
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*/
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int usb_enable_autosuspend(struct usb_device *udev)
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{
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if (udev->autosuspend_disabled) {
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udev->autosuspend_disabled = 0;
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usb_autosuspend_device(udev);
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}
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return 0;
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}
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EXPORT_SYMBOL_GPL(usb_enable_autosuspend);
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/**
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* usb_disable_autosuspend - prevent a USB device from being autosuspended
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* @udev: the USB device which may not be autosuspended
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*
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* This routine prevents @udev from being autosuspended and wakes it up
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* if it is already autosuspended.
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*
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* The caller must hold @udev's device lock.
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*/
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int usb_disable_autosuspend(struct usb_device *udev)
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{
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int rc = 0;
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if (!udev->autosuspend_disabled) {
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rc = usb_autoresume_device(udev);
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if (rc == 0)
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udev->autosuspend_disabled = 1;
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}
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return rc;
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}
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EXPORT_SYMBOL_GPL(usb_disable_autosuspend);
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/* Internal routine to adjust a device's usage counter and change
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* its autosuspend state.
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*/
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@ -1224,6 +1224,9 @@ static int hub_probe(struct usb_interface *intf, const struct usb_device_id *id)
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desc = intf->cur_altsetting;
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hdev = interface_to_usbdev(intf);
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/* Hubs have proper suspend/resume support */
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usb_enable_autosuspend(hdev);
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if (hdev->level == MAX_TOPO_LEVEL) {
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dev_err(&intf->dev,
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"Unsupported bus topology: hub nested too deep\n");
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@ -103,11 +103,10 @@ void usb_detect_quirks(struct usb_device *udev)
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dev_dbg(&udev->dev, "USB quirks for this device: %x\n",
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udev->quirks);
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/* By default, disable autosuspend for all non-hubs */
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#ifdef CONFIG_USB_SUSPEND
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if (udev->descriptor.bDeviceClass != USB_CLASS_HUB)
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udev->autosuspend_disabled = 1;
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#endif
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/* By default, disable autosuspend for all devices. The hub driver
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* will enable it for hubs.
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*/
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usb_disable_autosuspend(udev);
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/* For the present, all devices default to USB-PERSIST enabled */
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#if 0 /* was: #ifdef CONFIG_PM */
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@ -389,34 +389,25 @@ set_level(struct device *dev, struct device_attribute *attr,
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struct usb_device *udev = to_usb_device(dev);
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int len = count;
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char *cp;
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int rc = 0;
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int old_autosuspend_disabled;
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int rc;
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cp = memchr(buf, '\n', count);
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if (cp)
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len = cp - buf;
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usb_lock_device(udev);
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old_autosuspend_disabled = udev->autosuspend_disabled;
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/* Setting the flags without calling usb_pm_lock is a subject to
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* races, but who cares...
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*/
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if (len == sizeof on_string - 1 &&
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strncmp(buf, on_string, len) == 0) {
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udev->autosuspend_disabled = 1;
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rc = usb_external_resume_device(udev, PMSG_USER_RESUME);
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strncmp(buf, on_string, len) == 0)
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rc = usb_disable_autosuspend(udev);
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} else if (len == sizeof auto_string - 1 &&
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strncmp(buf, auto_string, len) == 0) {
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udev->autosuspend_disabled = 0;
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rc = usb_external_resume_device(udev, PMSG_USER_RESUME);
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else if (len == sizeof auto_string - 1 &&
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strncmp(buf, auto_string, len) == 0)
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rc = usb_enable_autosuspend(udev);
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} else
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else
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rc = -EINVAL;
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if (rc)
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udev->autosuspend_disabled = old_autosuspend_disabled;
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usb_unlock_device(udev);
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return (rc < 0 ? rc : count);
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}
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@ -542,6 +542,9 @@ extern struct usb_device *usb_find_device(u16 vendor_id, u16 product_id);
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/* USB autosuspend and autoresume */
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#ifdef CONFIG_USB_SUSPEND
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extern int usb_enable_autosuspend(struct usb_device *udev);
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extern int usb_disable_autosuspend(struct usb_device *udev);
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extern int usb_autopm_get_interface(struct usb_interface *intf);
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extern void usb_autopm_put_interface(struct usb_interface *intf);
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extern int usb_autopm_get_interface_async(struct usb_interface *intf);
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@ -565,6 +568,11 @@ static inline void usb_mark_last_busy(struct usb_device *udev)
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#else
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static inline int usb_enable_autosuspend(struct usb_device *udev)
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{ return 0; }
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static inline int usb_disable_autosuspend(struct usb_device *udev)
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{ return 0; }
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static inline int usb_autopm_get_interface(struct usb_interface *intf)
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{ return 0; }
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static inline int usb_autopm_get_interface_async(struct usb_interface *intf)
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