USB: musb: rewrite host periodic endpoint allocation

The current MUSB host code doesn't make use of all the available
FIFOs in for periodic transfers since it wrongly assumes the RX
and TX sides of any given hw_ep always share one FIFO.

Change:  use 'in_qh' and 'out_qh' fields of the 'struct musb_hw_ep'
to check the endpoint's business; get rid of the now-unused 'periodic'
array in the 'struct musb'.  Also optimize a loop induction variable
in the endpoint lookup code.

(Based on a previous patch from Ajay Kumar Gupta <ajay.gupta@ti.com>)

[ dbrownell@users.sourceforge.net: clarify description and origin
  of this fix; whitespace ]
Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Felipe Balbi <felipe.balbi@nokia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/musb/musb_core.h

@@ -331,7 +331,6 @@ struct musb {
 	struct list_head	control;	/* of musb_qh */
 	struct list_head	in_bulk;	/* of musb_qh */
 	struct list_head	out_bulk;	/* of musb_qh */
-	struct musb_qh		*periodic[32];	/* tree of interrupt+iso */
 #endif
 
 	/* called with IRQs blocked; ON/nonzero implies starting a session,

drivers/usb/musb/musb_host.c

@@ -395,7 +395,6 @@ musb_giveback(struct musb_qh *qh, struct urb *urb, int status)
 			 * de-allocated if it's tracked and allocated;
 			 * and where we'd update the schedule tree...
 			 */
-			musb->periodic[ep->epnum] = NULL;
 			kfree(qh);
 			qh = NULL;
 			break;
@@ -1711,31 +1710,27 @@ static int musb_schedule(
 
 	/* else, periodic transfers get muxed to other endpoints */
 
-	/* FIXME this doesn't consider direction, so it can only
-	 * work for one half of the endpoint hardware, and assumes
-	 * the previous cases handled all non-shared endpoints...
-	 */
-
-	/* we know this qh hasn't been scheduled, so all we need to do
+	/*
+	 * We know this qh hasn't been scheduled, so all we need to do
 	 * is choose which hardware endpoint to put it on ...
 	 *
 	 * REVISIT what we really want here is a regular schedule tree
-	 * like e.g. OHCI uses, but for now musb->periodic is just an
-	 * array of the _single_ logical endpoint associated with a
-	 * given physical one (identity mapping logical->physical).
-	 *
-	 * that simplistic approach makes TT scheduling a lot simpler;
-	 * there is none, and thus none of its complexity...
+	 * like e.g. OHCI uses.
 	 */
 	best_diff = 4096;
 	best_end = -1;
 
-	for (epnum = 1; epnum < musb->nr_endpoints; epnum++) {
+	for (epnum = 1, hw_ep = musb->endpoints + 1;
+			epnum < musb->nr_endpoints;
+			epnum++, hw_ep++) {
 		int	diff;
 
-		if (musb->periodic[epnum])
+		if (is_in || hw_ep->is_shared_fifo) {
+			if (hw_ep->in_qh  != NULL)
+				continue;
+		} else	if (hw_ep->out_qh != NULL)
 			continue;
-		hw_ep = &musb->endpoints[epnum];
+
 		if (hw_ep == musb->bulk_ep)
 			continue;
 
@@ -1764,7 +1759,6 @@ static int musb_schedule(
 	idle = 1;
 	qh->mux = 0;
 	hw_ep = musb->endpoints + best_end;
-	musb->periodic[best_end] = qh;
 	DBG(4, "qh %p periodic slot %d\n", qh, best_end);
 success:
 	if (head) {