From: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
---
Documentation/usb/power-management.txt | 18 +++++++++++++
drivers/usb/core/driver.c | 42 ++++++++++++++++++++++++++++++++
drivers/usb/core/hub.c | 3 ++
drivers/usb/core/quirks.c | 9 +++----
drivers/usb/core/sysfs.c | 23 +++++------------
include/linux/usb.h | 8 ++++++
6 files changed, 82 insertions(+), 21 deletions(-)
diff --git a/Documentation/usb/power-management.txt b/Documentation/usb/power-management.txt
index 3bf6818..e3fa189 100644
--- a/Documentation/usb/power-management.txt
+++ b/Documentation/usb/power-management.txt
@@ -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
diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
index 2b39583..057eeab 100644
--- a/drivers/usb/core/driver.c
+++ b/drivers/usb/core/driver.c
@@ -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.
*/
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index bfa6123..746f26f 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -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");
diff --git a/drivers/usb/core/quirks.c b/drivers/usb/core/quirks.c
index 0b68922..4314f25 100644
--- a/drivers/usb/core/quirks.c
+++ b/drivers/usb/core/quirks.c
@@ -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 */
diff --git a/drivers/usb/core/sysfs.c b/drivers/usb/core/sysfs.c
index 5a1a0e2..313e241 100644
--- a/drivers/usb/core/sysfs.c
+++ b/drivers/usb/core/sysfs.c
@@ -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);
}
diff --git a/include/linux/usb.h b/include/linux/usb.h
index 332eaea..e6419ac 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -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)
--
1.7.0.1
--
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