USB: make autosuspend delay a module parameter

This patch (as859) makes the default USB autosuspend delay a module
parameter of usbcore.  By setting the delay value at boot time, users
will be able to prevent the system from autosuspending devices which
for some reason can't handle it.

The patch also stores the autosuspend delay as a per-device value.  A
later patch will allow the user to change the value, tailoring the
delay for each individual device.  A delay value of 0 will prevent
autosuspend.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

Documentation/kernel-parameters.txt

@@ -1758,6 +1758,13 @@ and is between 256 and 4096 characters. It is defined in the file
 			Note that genuine overcurrent events won't be
 			reported either.
 
+	usbcore.autosuspend=
+			[USB] The autosuspend time delay (in seconds) used
+			for newly-detected USB devices (default 2).  This
+			is the time required before an idle device will be
+			autosuspended.  Devices for which the delay is set
+			to 0 won't be autosuspended at all.
+
 	usbhid.mousepoll=
 			[USBHID] The interval which mice are to be polled at.
 

drivers/usb/core/driver.c

@@ -963,12 +963,16 @@ static int autosuspend_check(struct usb_device *udev)
 	int			i;
 	struct usb_interface	*intf;
 
-	/* For autosuspend, fail fast if anything is in use.
-	 * Also fail if any interfaces require remote wakeup but it
-	 * isn't available. */
+	/* For autosuspend, fail fast if anything is in use or autosuspend
+	 * is disabled.  Also fail if any interfaces require remote wakeup
+	 * but it isn't available.
+	 */
 	udev->do_remote_wakeup = device_may_wakeup(&udev->dev);
 	if (udev->pm_usage_cnt > 0)
 		return -EBUSY;
+	if (!udev->autosuspend_delay)
+		return -EPERM;
+
 	if (udev->actconfig) {
 		for (i = 0; i < udev->actconfig->desc.bNumInterfaces; i++) {
 			intf = udev->actconfig->interface[i];
@@ -991,7 +995,7 @@ static int autosuspend_check(struct usb_device *udev)
 
 #define autosuspend_check(udev)		0
 
-#endif
+#endif	/* CONFIG_USB_SUSPEND */
 
 /**
  * usb_suspend_both - suspend a USB device and its interfaces
@@ -1186,7 +1190,7 @@ static int usb_autopm_do_device(struct usb_device *udev, int inc_usage_cnt)
 			udev->pm_usage_cnt -= inc_usage_cnt;
 	} else if (inc_usage_cnt <= 0 && autosuspend_check(udev) == 0)
 		queue_delayed_work(ksuspend_usb_wq, &udev->autosuspend,
-				USB_AUTOSUSPEND_DELAY);
+				udev->autosuspend_delay);
 	usb_pm_unlock(udev);
 	return status;
 }
@@ -1270,7 +1274,7 @@ static int usb_autopm_do_interface(struct usb_interface *intf,
 				intf->pm_usage_cnt -= inc_usage_cnt;
 		} else if (inc_usage_cnt <= 0 && autosuspend_check(udev) == 0)
 			queue_delayed_work(ksuspend_usb_wq, &udev->autosuspend,
-					USB_AUTOSUSPEND_DELAY);
+					udev->autosuspend_delay);
 	}
 	usb_pm_unlock(udev);
 	return status;

drivers/usb/core/quirks.c

@@ -39,8 +39,10 @@ static const struct usb_device_id usb_quirk_list[] = {
 
 static void usb_autosuspend_quirk(struct usb_device *udev)
 {
-	/* unbalanced resume to prevent autosuspends */
-	usb_autoresume_device(udev);
+#ifdef	CONFIG_USB_SUSPEND
+	/* disable autosuspend, but allow the user to re-enable it via sysfs */
+	udev->autosuspend_delay = 0;
+#endif
 }
 
 static const struct usb_device_id *find_id(struct usb_device *udev)

drivers/usb/core/usb.c

@@ -22,6 +22,7 @@
  */
 
 #include <linux/module.h>
+#include <linux/moduleparam.h>
 #include <linux/string.h>
 #include <linux/bitops.h>
 #include <linux/slab.h>
@@ -50,6 +51,16 @@ static int nousb;	/* Disable USB when built into kernel image */
 
 struct workqueue_struct *ksuspend_usb_wq;	/* For autosuspend */
 
+#ifdef	CONFIG_USB_SUSPEND
+static int usb_autosuspend_delay = 2;		/* Default delay value,
+						 * in seconds */
+module_param_named(autosuspend, usb_autosuspend_delay, uint, 0644);
+MODULE_PARM_DESC(autosuspend, "default autosuspend delay");
+
+#else
+#define usb_autosuspend_delay		0
+#endif
+
 
 /**
  * usb_ifnum_to_if - get the interface object with a given interface number
@@ -306,6 +317,7 @@ usb_alloc_dev(struct usb_device *parent, struct usb_bus *bus, unsigned port1)
 #ifdef	CONFIG_PM
 	mutex_init(&dev->pm_mutex);
 	INIT_DELAYED_WORK(&dev->autosuspend, usb_autosuspend_work);
+	dev->autosuspend_delay = usb_autosuspend_delay * HZ;
 #endif
 	return dev;
 }

drivers/usb/core/usb.h

@@ -65,8 +65,6 @@ static inline void usb_pm_unlock(struct usb_device *udev) {}
 
 #ifdef CONFIG_USB_SUSPEND
 
-#define USB_AUTOSUSPEND_DELAY	(HZ*2)
-
 extern void usb_autosuspend_device(struct usb_device *udev);
 extern int usb_autoresume_device(struct usb_device *udev);
 

include/linux/usb.h

@@ -389,10 +389,13 @@ struct usb_device {
 
 	int pm_usage_cnt;		/* usage counter for autosuspend */
 	u32 quirks;			/* quirks of the whole device */
+
 #ifdef CONFIG_PM
 	struct delayed_work autosuspend; /* for delayed autosuspends */
 	struct mutex pm_mutex;		/* protects PM operations */
 
+	unsigned autosuspend_delay;	/* in jiffies */
+
 	unsigned auto_pm:1;		/* autosuspend/resume in progress */
 	unsigned do_remote_wakeup:1;	/* remote wakeup should be enabled */
 #endif