Commit 088f7fec authored by Alan Stern's avatar Alan Stern Committed by Greg Kroah-Hartman

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: default avatarAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 0c4db6df
......@@ -229,6 +229,11 @@ necessary operations by hand or add them to a udev script. You can
also change the idle-delay time; 2 seconds is not the best choice for
every device.
If a driver knows that its device has proper suspend/resume support,
it can enable autosuspend all by itself. For example, the video
driver for a laptop's webcam might do this, since these devices are
rarely used and so should normally be autosuspended.
Sometimes it turns out that even when a device does work okay with
autosuspend there are still problems. For example, there are
experimental patches adding autosuspend support to the usbhid driver,
......@@ -384,6 +389,19 @@ autosuspend, there's no delay for an autoresume.
Other parts of the driver interface
-----------------------------------
Drivers can enable autosuspend for their devices by calling
usb_enable_autosuspend(struct usb_device *udev);
in their probe() routine, if they know that the device is capable of
suspending and resuming correctly. This is exactly equivalent to
writing "auto" to the device's power/level attribute. Likewise,
drivers can disable autosuspend by calling
usb_disable_autosuspend(struct usb_device *udev);
This is exactly the same as writing "on" to the power/level attribute.
Sometimes a driver needs to make sure that remote wakeup is enabled
during autosuspend. For example, there's not much point
autosuspending a keyboard if the user can't cause the keyboard to do a
......
......@@ -1415,6 +1415,48 @@ static int usb_resume_both(struct usb_device *udev, pm_message_t msg)
#ifdef CONFIG_USB_SUSPEND
/**
* usb_enable_autosuspend - allow a USB device to be autosuspended
* @udev: the USB device which may be autosuspended
*
* This routine allows @udev to be autosuspended. An autosuspend won't
* take place until the autosuspend_delay has elapsed and all the other
* necessary conditions are satisfied.
*
* The caller must hold @udev's device lock.
*/
int usb_enable_autosuspend(struct usb_device *udev)
{
if (udev->autosuspend_disabled) {
udev->autosuspend_disabled = 0;
usb_autosuspend_device(udev);
}
return 0;
}
EXPORT_SYMBOL_GPL(usb_enable_autosuspend);
/**
* usb_disable_autosuspend - prevent a USB device from being autosuspended
* @udev: the USB device which may not be autosuspended
*
* This routine prevents @udev from being autosuspended and wakes it up
* if it is already autosuspended.
*
* The caller must hold @udev's device lock.
*/
int usb_disable_autosuspend(struct usb_device *udev)
{
int rc = 0;
if (!udev->autosuspend_disabled) {
rc = usb_autoresume_device(udev);
if (rc == 0)
udev->autosuspend_disabled = 1;
}
return rc;
}
EXPORT_SYMBOL_GPL(usb_disable_autosuspend);
/* Internal routine to adjust a device's usage counter and change
* its autosuspend state.
*/
......
......@@ -1224,6 +1224,9 @@ static int hub_probe(struct usb_interface *intf, const struct usb_device_id *id)
desc = intf->cur_altsetting;
hdev = interface_to_usbdev(intf);
/* Hubs have proper suspend/resume support */
usb_enable_autosuspend(hdev);
if (hdev->level == MAX_TOPO_LEVEL) {
dev_err(&intf->dev,
"Unsupported bus topology: hub nested too deep\n");
......
......@@ -103,11 +103,10 @@ void usb_detect_quirks(struct usb_device *udev)
dev_dbg(&udev->dev, "USB quirks for this device: %x\n",
udev->quirks);
/* By default, disable autosuspend for all non-hubs */
#ifdef CONFIG_USB_SUSPEND
if (udev->descriptor.bDeviceClass != USB_CLASS_HUB)
udev->autosuspend_disabled = 1;
#endif
/* By default, disable autosuspend for all devices. The hub driver
* will enable it for hubs.
*/
usb_disable_autosuspend(udev);
/* For the present, all devices default to USB-PERSIST enabled */
#if 0 /* was: #ifdef CONFIG_PM */
......
......@@ -389,34 +389,25 @@ set_level(struct device *dev, struct device_attribute *attr,
struct usb_device *udev = to_usb_device(dev);
int len = count;
char *cp;
int rc = 0;
int old_autosuspend_disabled;
int rc;
cp = memchr(buf, '\n', count);
if (cp)
len = cp - buf;
usb_lock_device(udev);
old_autosuspend_disabled = udev->autosuspend_disabled;
/* Setting the flags without calling usb_pm_lock is a subject to
* races, but who cares...
*/
if (len == sizeof on_string - 1 &&
strncmp(buf, on_string, len) == 0) {
udev->autosuspend_disabled = 1;
rc = usb_external_resume_device(udev, PMSG_USER_RESUME);
strncmp(buf, on_string, len) == 0)
rc = usb_disable_autosuspend(udev);
} else if (len == sizeof auto_string - 1 &&
strncmp(buf, auto_string, len) == 0) {
udev->autosuspend_disabled = 0;
rc = usb_external_resume_device(udev, PMSG_USER_RESUME);
else if (len == sizeof auto_string - 1 &&
strncmp(buf, auto_string, len) == 0)
rc = usb_enable_autosuspend(udev);
} else
else
rc = -EINVAL;
if (rc)
udev->autosuspend_disabled = old_autosuspend_disabled;
usb_unlock_device(udev);
return (rc < 0 ? rc : count);
}
......
......@@ -542,6 +542,9 @@ extern struct usb_device *usb_find_device(u16 vendor_id, u16 product_id);
/* USB autosuspend and autoresume */
#ifdef CONFIG_USB_SUSPEND
extern int usb_enable_autosuspend(struct usb_device *udev);
extern int usb_disable_autosuspend(struct usb_device *udev);
extern int usb_autopm_get_interface(struct usb_interface *intf);
extern void usb_autopm_put_interface(struct usb_interface *intf);
extern int usb_autopm_get_interface_async(struct usb_interface *intf);
......@@ -565,6 +568,11 @@ static inline void usb_mark_last_busy(struct usb_device *udev)
#else
static inline int usb_enable_autosuspend(struct usb_device *udev)
{ return 0; }
static inline int usb_disable_autosuspend(struct usb_device *udev)
{ return 0; }
static inline int usb_autopm_get_interface(struct usb_interface *intf)
{ return 0; }
static inline int usb_autopm_get_interface_async(struct usb_interface *intf)
......
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