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Commit e4e18cbd authored by Alan Stern's avatar Alan Stern Committed by Greg Kroah-Hartman
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USB: EHCI: code rearrangement in iso_stream_schedule() 



This patch interchanges the "if" and "else" branches of the big "if"
statement in iso_stream_schedule(), in preparation for the next patch
in this series.  That is, it changes

	if (likely(!...)) {
		A
	} else {
		B
	}

to

	if (unlikely(...)) {
		B
	} else {
		A
	}

Signed-off-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent c7ccde6e

drivers/usb/host/ehci-sched.c

+47 −45
Original line number Diff line number Diff line
@@ -1384,12 +1384,57 @@ iso_stream_schedule ( 


	now = ehci_read_frame_index(ehci) & (mod - 1);



	/* Typical case: reuse current schedule, stream is still active.

	/*

	 * Need to schedule; when's the next (u)frame we could start?

	 * This is bigger than ehci->i_thresh allows; scheduling itself

	 * isn't free, the delay should handle reasonably slow cpus.  It

	 * can also help high bandwidth if the dma and irq loads don't

	 * jump until after the queue is primed.

	 */

	if (unlikely(list_empty(&stream->td_list))) {

		int done = 0;



		base = now & ~0x07;

		start = base + SCHEDULING_DELAY;



		/* find a uframe slot with enough bandwidth.

		 * Early uframes are more precious because full-speed

		 * iso IN transfers can't use late uframes,

		 * and therefore they should be allocated last.

		 */

		next = start;

		start += period;

		do {

			start--;

			/* check schedule: enough space? */

			if (stream->highspeed) {

				if (itd_slot_ok(ehci, mod, start,

						stream->usecs, period))

					done = 1;

			} else {

				if ((start % 8) >= 6)

					continue;

				if (sitd_slot_ok(ehci, mod, stream,

						start, sched, period))

					done = 1;

			}

		} while (start > next && !done);



		/* no room in the schedule */

		if (!done) {

			ehci_dbg(ehci, "iso sched full %p", urb);

			status = -ENOSPC;

			goto fail;

		}

	}



	/*

	 * Typical case: reuse current schedule, stream is still active.

	 * Hopefully there are no gaps from the host falling behind

	 * (irq delays etc).  If there are, the behavior depends on

	 * whether URB_ISO_ASAP is set.

	 */

	if (likely (!list_empty (&stream->td_list))) {

	else {



		/* Take the isochronous scheduling threshold into account */

		if (ehci->i_thresh)
@@ -1436,49 +1481,6 @@ iso_stream_schedule ( 
		start += base;

	}



	/* need to schedule; when's the next (u)frame we could start?

	 * this is bigger than ehci->i_thresh allows; scheduling itself

	 * isn't free, the delay should handle reasonably slow cpus.  it

	 * can also help high bandwidth if the dma and irq loads don't

	 * jump until after the queue is primed.

	 */

	else {

		int done = 0;



		base = now & ~0x07;

		start = base + SCHEDULING_DELAY;



		/* find a uframe slot with enough bandwidth.

		 * Early uframes are more precious because full-speed

		 * iso IN transfers can't use late uframes,

		 * and therefore they should be allocated last.

		 */

		next = start;

		start += period;

		do {

			start--;

			/* check schedule: enough space? */

			if (stream->highspeed) {

				if (itd_slot_ok(ehci, mod, start,

						stream->usecs, period))

					done = 1;

			} else {

				if ((start % 8) >= 6)

					continue;

				if (sitd_slot_ok(ehci, mod, stream,

						start, sched, period))

					done = 1;

			}

		} while (start > next && !done);



		/* no room in the schedule */

		if (!done) {

			ehci_dbg(ehci, "iso sched full %p", urb);

			status = -ENOSPC;

			goto fail;

		}

	}



	/* Tried to schedule too far into the future? */

	if (unlikely(start - base + span - period >= mod)) {

		ehci_dbg(ehci, "request %p would overflow (%u+%u >= %u)\n",