Make sure that the USB system suspend event is executed synchronously

and not asynchronously. This fixes problems related to USB system
suspend and resume.  It is assumed that we are always allowed to sleep
from the device_suspend() method.

MFC after:	1 week
Submitted by:	jkim

1 files changed, 21 insertions, 2 deletions

diff --git a/sys/dev/usb/controller/usb_controller.c b/sys/dev/usb/controller/usb_controller.c
index 0f942e1..f678427 100644
--- a/sys/dev/usb/controller/usb_controller.c
+++ b/sys/dev/usb/controller/usb_controller.c
@@ -89,10 +89,15 @@ TUNABLE_INT("hw.usb.no_boot_wait", &usb_no_boot_wait);
 SYSCTL_INT(_hw_usb, OID_AUTO, no_boot_wait, CTLFLAG_RDTUN, &usb_no_boot_wait, 0,
     "No USB device enumerate waiting at boot.");
 
+static int usb_no_suspend_wait = 0;
+TUNABLE_INT("hw.usb.no_suspend_wait", &usb_no_suspend_wait);
+SYSCTL_INT(_hw_usb, OID_AUTO, no_suspend_wait, CTLFLAG_RW|CTLFLAG_TUN,
+    &usb_no_suspend_wait, 0, "No USB device waiting at system suspend.");
+
 static int usb_no_shutdown_wait = 0;
 TUNABLE_INT("hw.usb.no_shutdown_wait", &usb_no_shutdown_wait);
-SYSCTL_INT(_hw_usb, OID_AUTO, no_shutdown_wait, CTLFLAG_RW|CTLFLAG_TUN, &usb_no_shutdown_wait, 0,
-    "No USB device waiting at system shutdown.");
+SYSCTL_INT(_hw_usb, OID_AUTO, no_shutdown_wait, CTLFLAG_RW|CTLFLAG_TUN,
+    &usb_no_shutdown_wait, 0, "No USB device waiting at system shutdown.");
 
 static devclass_t usb_devclass;
 
@@ -240,6 +245,11 @@ usb_suspend(device_t dev)
 	USB_BUS_LOCK(bus);
 	usb_proc_msignal(&bus->explore_proc,
 	    &bus->suspend_msg[0], &bus->suspend_msg[1]);
+	if (usb_no_suspend_wait == 0) {
+		/* wait for suspend callback to be executed */
+		usb_proc_mwait(&bus->explore_proc,
+		    &bus->suspend_msg[0], &bus->suspend_msg[1]);
+	}
 	USB_BUS_UNLOCK(bus);
 
 	return (0);
@@ -407,6 +417,15 @@ usb_bus_suspend(struct usb_proc_msg *pm)
 
 	USB_BUS_UNLOCK(bus);
 
+	/*
+	 * We use the shutdown event here because the suspend and
+	 * resume events are reserved for the USB port suspend and
+	 * resume. The USB system suspend is implemented like full
+	 * shutdown and all connected USB devices will be disconnected
+	 * subsequently. At resume all USB devices will be
+	 * re-connected again.
+	 */
+
 	bus_generic_shutdown(bus->bdev);
 
 	usbd_enum_lock(udev);