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>
diff --git a/drivers/usb/host/ehci.h b/drivers/usb/host/ehci.h
index 3ce7249..ec0da03 100644
--- a/drivers/usb/host/ehci.h
+++ b/drivers/usb/host/ehci.h
@@ -74,7 +74,11 @@
/* 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 */