Alan Stern <stern@rowland.harvard.edu>
- October 5, 2007
+ November 10, 2009
power/level
- This file contains one of three words: "on", "auto",
- or "suspend". You can write those words to the file
- to change the device's setting.
+ This file contains one of two words: "on" or "auto".
+ You can write those words to the file to change the
+ device's setting.
"on" means that the device should be resumed and
autosuspend is not allowed. (Of course, system
"auto" is the normal state in which the kernel is
allowed to autosuspend and autoresume the device.
- "suspend" means that the device should remain
- suspended, and autoresume is not allowed. (But remote
- wakeup may still be allowed, since it is controlled
- separately by the power/wakeup attribute.)
+ (In kernels up to 2.6.32, you could also specify
+ "suspend", meaning that the device should remain
+ suspended and autoresume was not allowed. This
+ setting is no longer supported.)
power/autosuspend
that it supports autosuspend by setting the .supports_autosuspend flag
in its usb_driver structure. It is then responsible for informing the
USB core whenever one of its interfaces becomes busy or idle. The
-driver does so by calling these five functions:
+driver does so by calling these six functions:
int usb_autopm_get_interface(struct usb_interface *intf);
void usb_autopm_put_interface(struct usb_interface *intf);
- int usb_autopm_set_interface(struct usb_interface *intf);
int usb_autopm_get_interface_async(struct usb_interface *intf);
void usb_autopm_put_interface_async(struct usb_interface *intf);
+ void usb_autopm_get_interface_no_resume(struct usb_interface *intf);
+ void usb_autopm_put_interface_no_suspend(struct usb_interface *intf);
The functions work by maintaining a counter in the usb_interface
structure. When intf->pm_usage_count is > 0 then the interface is
associated with the device itself rather than any of its interfaces.
This field is used only by the USB core.)
-The driver owns intf->pm_usage_count; it can modify the value however
-and whenever it likes. A nice aspect of the non-async usb_autopm_*
-routines is that the changes they make are protected by the usb_device
-structure's PM mutex (udev->pm_mutex); however drivers may change
-pm_usage_count without holding the mutex. Drivers using the async
+Drivers must not modify intf->pm_usage_count directly; its value
+should be changed only be using the functions listed above. Drivers
+are responsible for insuring that the overall change to pm_usage_count
+during their lifetime balances out to 0 (it may be necessary for the
+disconnect method to call usb_autopm_put_interface() one or more times
+to fulfill this requirement). The first two routines use the PM mutex
+in struct usb_device for mutual exclusion; drivers using the async
routines are responsible for their own synchronization and mutual
exclusion.
attempts an autosuspend if the new value is <= 0 and the
device isn't suspended.
- usb_autopm_set_interface() leaves pm_usage_count alone.
- It attempts an autoresume if the value is > 0 and the device
- is suspended, and it attempts an autosuspend if the value is
- <= 0 and the device isn't suspended.
-
usb_autopm_get_interface_async() and
usb_autopm_put_interface_async() do almost the same things as
their non-async counterparts. The differences are: they do
such as an URB's completion handler, but when they return the
device will not generally not yet be in the desired state.
-There also are a couple of utility routines drivers can use:
-
- usb_autopm_enable() sets pm_usage_cnt to 0 and then calls
- usb_autopm_set_interface(), which will attempt an autosuspend.
-
- usb_autopm_disable() sets pm_usage_cnt to 1 and then calls
- usb_autopm_set_interface(), which will attempt an autoresume.
+ usb_autopm_get_interface_no_resume() and
+ usb_autopm_put_interface_no_suspend() merely increment or
+ decrement the pm_usage_count value; they do not attempt to
+ carry out an autoresume or an autosuspend. Hence they can be
+ called in an atomic context.
The conventional usage pattern is that a driver calls
usb_autopm_get_interface() in its open routine and
Normally a driver would set this flag in its probe method, at which
time the device is guaranteed not to be autosuspended.)
-The usb_autopm_* routines have to run in a sleepable process context;
-they must not be called from an interrupt handler or while holding a
-spinlock. In fact, the entire autosuspend mechanism is not well geared
-toward interrupt-driven operation. However there is one thing a
-driver can do in an interrupt handler:
+The synchronous usb_autopm_* routines have to run in a sleepable
+process context; they must not be called from an interrupt handler or
+while holding a spinlock. In fact, the entire autosuspend mechanism
+is not well geared toward interrupt-driven operation. However there
+is one thing a driver can do in an interrupt handler:
usb_mark_last_busy(struct usb_device *udev);
done:
dev_vdbg(&udev->dev, "%s: status %d\n", __func__, status);
- if (status == 0)
- udev->autoresume_disabled = 0;
return status;
}
/* Propagate the resume up the tree, if necessary */
if (udev->state == USB_STATE_SUSPENDED) {
- if ((msg.event & PM_EVENT_AUTO) &&
- udev->autoresume_disabled) {
- status = -EPERM;
- goto done;
- }
if (parent) {
status = usb_autoresume_device(parent);
if (status == 0) {
if (intf->condition == USB_INTERFACE_UNBOUND)
status = -ENODEV;
- else if (udev->autoresume_disabled)
- status = -EPERM;
else {
atomic_inc(&intf->pm_usage_cnt);
if (atomic_read(&intf->pm_usage_cnt) > 0 &&
}
EXPORT_SYMBOL_GPL(usb_autopm_get_interface_async);
-/**
- * usb_autopm_set_interface - set a USB interface's autosuspend state
- * @intf: the usb_interface whose state should be set
- *
- * This routine sets the autosuspend state of @intf's device according
- * to @intf's usage counter, which the caller must have set previously.
- * If the counter is <= 0, the device is autosuspended (if it isn't
- * already suspended and if nothing else prevents the autosuspend). If
- * the counter is > 0, the device is autoresumed (if it isn't already
- * awake).
- */
-int usb_autopm_set_interface(struct usb_interface *intf)
-{
- int status;
-
- status = usb_autopm_do_interface(intf, 0);
- dev_vdbg(&intf->dev, "%s: status %d cnt %d\n",
- __func__, status, atomic_read(&intf->pm_usage_cnt));
- return status;
-}
-EXPORT_SYMBOL_GPL(usb_autopm_set_interface);
-
#else
void usb_autosuspend_work(struct work_struct *work)
unsigned mA_per_port; /* current for each child */
+ unsigned init_done:1;
unsigned limited_power:1;
unsigned quiescing:1;
unsigned disconnected:1;
{
unsigned long flags;
- /* Suppress autosuspend until khubd runs */
- atomic_set(&to_usb_interface(hub->intfdev)->pm_usage_cnt, 1);
-
spin_lock_irqsave(&hub_event_lock, flags);
if (!hub->disconnected && list_empty(&hub->event_list)) {
list_add_tail(&hub->event_list, &hub_event_list);
+
+ /* Suppress autosuspend until khubd runs */
+ usb_autopm_get_interface_no_resume(
+ to_usb_interface(hub->intfdev));
wake_up(&khubd_wait);
}
spin_unlock_irqrestore(&hub_event_lock, flags);
}
enum hub_activation_type {
- HUB_INIT, HUB_INIT2, HUB_INIT3,
+ HUB_INIT, HUB_INIT2, HUB_INIT3, /* INITs must come first */
HUB_POST_RESET, HUB_RESUME, HUB_RESET_RESUME,
};
msecs_to_jiffies(delay));
/* Suppress autosuspend until init is done */
- atomic_set(&to_usb_interface(hub->intfdev)->
- pm_usage_cnt, 1);
+ usb_autopm_get_interface_no_resume(
+ to_usb_interface(hub->intfdev));
return; /* Continues at init2: below */
} else {
hub_power_on(hub, true);
}
init3:
hub->quiescing = 0;
+ hub->init_done = 1;
status = usb_submit_urb(hub->urb, GFP_NOIO);
if (status < 0)
/* Scan all ports that need attention */
kick_khubd(hub);
+
+ /* Allow autosuspend if it was suppressed */
+ if (type <= HUB_INIT3)
+ usb_autopm_put_interface_async(to_usb_interface(hub->intfdev));
}
/* Implement the continuations for the delays above */
int i;
cancel_delayed_work_sync(&hub->init_work);
+ if (!hub->init_done) {
+ hub->init_done = 1;
+ usb_autopm_put_interface_no_suspend(
+ to_usb_interface(hub->intfdev));
+ }
/* khubd and related activity won't re-trigger */
hub->quiescing = 1;
/* Take the hub off the event list and don't let it be added again */
spin_lock_irq(&hub_event_lock);
- list_del_init(&hub->event_list);
+ if (!list_empty(&hub->event_list)) {
+ list_del_init(&hub->event_list);
+ usb_autopm_put_interface_no_suspend(intf);
+ }
hub->disconnected = 1;
spin_unlock_irq(&hub_event_lock);
* disconnected while waiting for the lock to succeed. */
usb_lock_device(hdev);
if (unlikely(hub->disconnected))
- goto loop;
+ goto loop2;
/* If the hub has died, clean up after it */
if (hdev->state == USB_STATE_NOTATTACHED) {
}
}
-loop_autopm:
- /* Allow autosuspend if we're not going to run again */
- if (list_empty(&hub->event_list))
- usb_autopm_enable(intf);
-loop:
+ loop_autopm:
+ /* Balance the usb_autopm_get_interface() above */
+ usb_autopm_put_interface_no_suspend(intf);
+ loop:
+ /* Balance the usb_autopm_get_interface_no_resume() in
+ * kick_khubd() and allow autosuspend.
+ */
+ usb_autopm_put_interface(intf);
+ loop2:
usb_unlock_device(hdev);
kref_put(&hub->kref, hub_release);
static const char on_string[] = "on";
static const char auto_string[] = "auto";
-static const char suspend_string[] = "suspend";
static ssize_t
show_level(struct device *dev, struct device_attribute *attr, char *buf)
struct usb_device *udev = to_usb_device(dev);
const char *p = auto_string;
- if (udev->state == USB_STATE_SUSPENDED) {
- if (udev->autoresume_disabled)
- p = suspend_string;
- } else {
- if (udev->autosuspend_disabled)
- p = on_string;
- }
+ if (udev->state != USB_STATE_SUSPENDED && udev->autosuspend_disabled)
+ p = on_string;
return sprintf(buf, "%s\n", p);
}
int len = count;
char *cp;
int rc = 0;
- int old_autosuspend_disabled, old_autoresume_disabled;
+ int old_autosuspend_disabled;
cp = memchr(buf, '\n', count);
if (cp)
usb_lock_device(udev);
old_autosuspend_disabled = udev->autosuspend_disabled;
- old_autoresume_disabled = udev->autoresume_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;
- udev->autoresume_disabled = 0;
rc = usb_external_resume_device(udev, PMSG_USER_RESUME);
} else if (len == sizeof auto_string - 1 &&
strncmp(buf, auto_string, len) == 0) {
udev->autosuspend_disabled = 0;
- udev->autoresume_disabled = 0;
rc = usb_external_resume_device(udev, PMSG_USER_RESUME);
- } else if (len == sizeof suspend_string - 1 &&
- strncmp(buf, suspend_string, len) == 0) {
- udev->autosuspend_disabled = 0;
- udev->autoresume_disabled = 1;
- rc = usb_external_suspend_device(udev, PMSG_USER_SUSPEND);
-
} else
rc = -EINVAL;
- if (rc) {
+ if (rc)
udev->autosuspend_disabled = old_autosuspend_disabled;
- udev->autoresume_disabled = old_autoresume_disabled;
- }
usb_unlock_device(udev);
return (rc < 0 ? rc : count);
}
* @do_remote_wakeup: remote wakeup should be enabled
* @reset_resume: needs reset instead of resume
* @autosuspend_disabled: autosuspend disabled by the user
- * @autoresume_disabled: autoresume disabled by the user
* @skip_sys_resume: skip the next system resume
* @wusb_dev: if this is a Wireless USB device, link to the WUSB
* specific data for the device.
unsigned do_remote_wakeup:1;
unsigned reset_resume:1;
unsigned autosuspend_disabled:1;
- unsigned autoresume_disabled:1;
unsigned skip_sys_resume:1;
#endif
struct wusb_dev *wusb_dev;
/* USB autosuspend and autoresume */
#ifdef CONFIG_USB_SUSPEND
-extern int usb_autopm_set_interface(struct usb_interface *intf);
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);
extern void usb_autopm_put_interface_async(struct usb_interface *intf);
-static inline void usb_autopm_enable(struct usb_interface *intf)
+static inline void usb_autopm_get_interface_no_resume(
+ struct usb_interface *intf)
{
- atomic_set(&intf->pm_usage_cnt, 0);
- usb_autopm_set_interface(intf);
+ atomic_inc(&intf->pm_usage_cnt);
}
-
-static inline void usb_autopm_disable(struct usb_interface *intf)
+static inline void usb_autopm_put_interface_no_suspend(
+ struct usb_interface *intf)
{
- atomic_set(&intf->pm_usage_cnt, 1);
- usb_autopm_set_interface(intf);
+ atomic_dec(&intf->pm_usage_cnt);
}
static inline void usb_mark_last_busy(struct usb_device *udev)
#else
-static inline int usb_autopm_set_interface(struct usb_interface *intf)
-{ 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)
{ return 0; }
{ }
static inline void usb_autopm_put_interface_async(struct usb_interface *intf)
{ }
-static inline void usb_autopm_enable(struct usb_interface *intf)
+static inline void usb_autopm_get_interface_no_resume(
+ struct usb_interface *intf)
{ }
-static inline void usb_autopm_disable(struct usb_interface *intf)
+static inline void usb_autopm_put_interface_no_suspend(
+ struct usb_interface *intf)
{ }
static inline void usb_mark_last_busy(struct usb_device *udev)
{ }
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