[v2] usb: core: make default autosuspend delay configurable

["Måns Rullgård" <mans@mansr.com>]

Make the default autosuspend delay configurable at build time.
This is useful for systems that require a non-standard value as
it avoids relying on the command line being properly set.

Signed-off-by: Mans Rullgard <mans@mansr.com>
---
Changes in v2:
- add explanatory text to Kconfig help
---
 drivers/usb/core/Kconfig | 12 ++++++++++++
 drivers/usb/core/usb.c   |  4 ++--
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/core/Kconfig b/drivers/usb/core/Kconfig
index 4d75d9a80001..cd91006e3f84 100644
--- a/drivers/usb/core/Kconfig
+++ b/drivers/usb/core/Kconfig
@@ -90,3 +90,15 @@ config USB_LEDS_TRIGGER_USBPORT
 	  This driver allows LEDs to be controlled by USB events. Enabling this
 	  trigger allows specifying list of USB ports that should turn on LED
 	  when some USB device gets connected.
+
+config USB_AUTOSUSPEND_DELAY
+	int "Default autosuspend delay"
+	depends on USB
+	default 2
+	help
+	  The default autosuspend delay in seconds.  Can be overridden
+	  with the usbcore.autosuspend command line or module parameter.
+
+	  The default value Linux has always had is 2 seconds.  Change
+	  this value if you want a different delay and cannot modify
+	  the command line or module parameter.
diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c
index 4ebfbd737905..52e749386c1c 100644
--- a/drivers/usb/core/usb.c
+++ b/drivers/usb/core/usb.c
@@ -65,8 +65,8 @@ int usb_disabled(void)
 EXPORT_SYMBOL_GPL(usb_disabled);
 
 #ifdef	CONFIG_PM
-static int usb_autosuspend_delay = 2;		/* Default delay value,
-						 * in seconds */
+/* Default delay value, in seconds */
+static int usb_autosuspend_delay = CONFIG_USB_AUTOSUSPEND_DELAY;
 module_param_named(autosuspend, usb_autosuspend_delay, int, 0644);
 MODULE_PARM_DESC(autosuspend, "default autosuspend delay");