EHCI: force high-speed devices to run at full speed

This patch (as710) adds a sysfs class-device attribute file named
"companion" for EHCI controllers.  The file contains a list of port
numbers that are dedicated to the companion controller; by writing a
port number to the file the user can force a high-speed device
attached directly to the computer to run at full speed.  (As far as I
know it is not possible to do this for a device attached to an
external hub.)  A port is removed from the file by writing the
negative of its port number.

Several users have asked for this facility and it seems like a useful
thing to have.  Every now and then one runs across a device which
behaves much better at full speed than at high speed.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 5 insertions, 1 deletions

diff --git a/drivers/usb/host/ehci.h b/drivers/usb/host/ehci.h
index 3ce7249085d5..ec0da0343be4 100644
--- a/drivers/usb/host/ehci.h
+++ b/drivers/usb/host/ehci.h
@@ -74,7 +74,11 @@ struct ehci_hcd {			/* one per controller */
 
         /* per root hub port */
         unsigned long           reset_done [EHCI_MAX_ROOT_PORTS];
-        unsigned long           bus_suspended;
+        /* bit vectors (one bit per port) */
+        unsigned long           bus_suspended;          /* which ports were
+                        already suspended at the start of a bus suspend */
+        unsigned long           companion_ports;        /* which ports are
+                        dedicated to the companion controller */
 
         /* per-HC memory pools (could be per-bus, but ...) */
         struct dma_pool         *qh_pool;       /* qh per active urb */