USB: ehci saves some memory in ISO transfer descriptors

In the EHCI driver, itd->usecs[8] is used in periodic_usecs(), indexed by
uframe.  For an ITD's unused uframes it is 0, else it contains the same
value as itd->stream->usecs.  To check if an ITD's uframe is used, we can
instead test itd->hw_transaction[uframe]:  if used, it will be nonzero no
matter what endianess is used.

This patch replaces those two uses, eliminates itd->usecs[], and saves
eight bytes from each ITD.

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

drivers/usb/host/ehci-sched.c

@@ -119,7 +119,8 @@ periodic_usecs (struct ehci_hcd *ehci, unsigned frame, unsigned uframe)
 			q = &q->fstn->fstn_next;
 			break;
 		case Q_TYPE_ITD:
-			usecs += q->itd->usecs [uframe];
+			if (q->itd->hw_transaction[uframe])
+				usecs += q->itd->stream->usecs;
 			hw_p = &q->itd->hw_next;
 			q = &q->itd->itd_next;
 			break;
@@ -1536,7 +1537,6 @@ itd_link_urb (
 		uframe = next_uframe & 0x07;
 		frame = next_uframe >> 3;
 
-		itd->usecs [uframe] = stream->usecs;
 		itd_patch(ehci, itd, iso_sched, packet, uframe);
 
 		next_uframe += stream->interval;

drivers/usb/host/ehci.h

@@ -602,7 +602,6 @@ struct ehci_itd {
 	unsigned		frame;		/* where scheduled */
 	unsigned		pg;
 	unsigned		index[8];	/* in urb->iso_frame_desc */
-	u8			usecs[8];
 } __attribute__ ((aligned (32)));
 
 /*-------------------------------------------------------------------------*/