uhci.c, speed improvements

Basically, the patch turns switching off FSBR into a lazy operation with
the assumption there will be another transfer shortly afterwards. This
works wonders for usb-storage for instance.

drivers/usb/uhci.c

@@ -53,11 +53,11 @@
 #include <asm/irq.h>
 #include <asm/system.h>
 
+#include "hcd.h"
 #include "uhci.h"
 
 #include <linux/pm.h>
 
-
 /*
  * Version Information
  */
@@ -65,7 +65,6 @@
 #define DRIVER_AUTHOR "Linus 'Frodo Rabbit' Torvalds, Johannes Erdfelt, Randy Dunlap, Georg Acher, Deti Fliegl, Thomas Sailer, Roman Weissgaerber"
 #define DRIVER_DESC "USB Universal Host Controller Interface driver"
 
-
 /*
  * debug = 0, no debugging messages
  * debug = 1, dump failed URB's except for stalls
@@ -100,6 +99,7 @@ static void wakeup_hc(struct uhci *uhci);
 
 /* If a transfer is still active after this much time, turn off FSBR */
 #define IDLE_TIMEOUT	(HZ / 20)	/* 50 ms */
+#define FSBR_DELAY	(HZ / 20)	/* 50 ms */
 
 #define MAX_URB_LOOP	2048		/* Maximum number of linked URB's */
 
@@ -766,7 +766,7 @@ static void uhci_dec_fsbr(struct uhci *uhci, struct urb *urb)
 	if ((!(urb->transfer_flags & USB_NO_FSBR)) && urbp->fsbr) {
 		urbp->fsbr = 0;
 		if (!--uhci->fsbr)
-			uhci->skel_term_qh->link = UHCI_PTR_TERM;
+			uhci->fsbrtimeout = jiffies + FSBR_DELAY;
 	}
 
 	spin_unlock_irqrestore(&uhci->frame_list_lock, flags);
@@ -2031,6 +2031,12 @@ static void rh_int_timer_do(unsigned long ptr)
 		uhci_unlink_urb(u);
 	}
 
+	/* Really disable FSBR */
+	if (!uhci->fsbr && uhci->fsbrtimeout && time_after_eq(jiffies, uhci->fsbrtimeout)) {
+		uhci->fsbrtimeout = 0;
+		uhci->skel_term_qh->link = UHCI_PTR_TERM;
+	}
+
 	/* enter global suspend if nothing connected */
 	if (!uhci->is_suspended && !ports_active(uhci))
 		suspend_hc(uhci);

drivers/usb/uhci.h

@@ -309,6 +309,7 @@ struct uhci {
 	spinlock_t frame_list_lock;
 	struct uhci_frame_list *fl;		/* P: uhci->frame_list_lock */
 	int fsbr;				/* Full speed bandwidth reclamation */
+	unsigned long fsbrtimeout;		/* FSBR delay */
 	int is_suspended;
 
 	/* Main list of URB's currently controlled by this HC */