USB: defines for USB "Link Power Management" (LPM) ECN

There's a new PM-related change notice for the USB 2.0 specification
called "Link Power Management" (LPM).  It defines a new "L1 Suspend"
state which resembles the current (L2) suspend state, except that it
can be entered and exited much more quickly.  It should thus be more
useful for runtime PM, even though it doesn't mandate reduced power
draw from VBUS.

This patch provides the relevant #defines for usbcore.  Actually
implementing these mechanisms requires host silicon that can generate
new USB packets, plus hubs handling some new requests and peripherals
which understand the new packets.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 11 insertions, 3 deletions

diff --git a/include/linux/usb/ch9.h b/include/linux/usb/ch9.h
index 7e1da17ca7ce..61fcbc2b97da 100644
--- a/include/linux/usb/ch9.h
+++ b/include/linux/usb/ch9.h
@@ -66,8 +66,8 @@
 #define USB_RECIP_ENDPOINT              0x02
 #define USB_RECIP_OTHER                 0x03
 /* From Wireless USB 1.0 */
-#define USB_RECIP_PORT                  0x04
-#define USB_RECIP_RPIPE                 0x05
+#define USB_RECIP_PORT                  0x04
+#define USB_RECIP_RPIPE         0x05
 
 /*
  * Standard requests, for the bRequest field of a SETUP packet.
@@ -102,10 +102,16 @@
 #define USB_REQ_LOOPBACK_DATA_READ      0x16
 #define USB_REQ_SET_INTERFACE_DS        0x17
 
+/* The Link Power Mangement (LPM) ECN defines USB_REQ_TEST_AND_SET command,
+ * used by hubs to put ports into a new L1 suspend state, except that it
+ * forgot to define its number ...
+ */
+
 /*
  * USB feature flags are written using USB_REQ_{CLEAR,SET}_FEATURE, and
  * are read as a bit array returned by USB_REQ_GET_STATUS.  (So there
- * are at most sixteen features of each type.)
+ * are at most sixteen features of each type.)  Hubs may also support a
+ * new USB_REQ_TEST_AND_SET_FEATURE to put ports into L1 suspend.
  */
 #define USB_DEVICE_SELF_POWERED         0       /* (read only) */
 #define USB_DEVICE_REMOTE_WAKEUP        1       /* dev may initiate wakeup */
@@ -575,6 +581,8 @@ enum usb_device_state {
         /* NOTE:  there are actually four different SUSPENDED
          * states, returning to POWERED, DEFAULT, ADDRESS, or
          * CONFIGURED respectively when SOF tokens flow again.
+         * At this level there's no difference between L1 and L2
+         * suspend states.  (L2 being original USB 1.1 suspend.)
          */
 };