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Commit e58dcebc authored by Alan Stern's avatar Alan Stern Committed by Greg Kroah-Hartman
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USB: UHCI: improve scheduling of interrupt URBs 



This patch (as1140) adds a little intelligence to the interrupt-URB
scheduler in uhci-hcd.  Right now the scheduler is stupid; every URB
having the same period is assigned to the same slot.  Thus a large
group of period-N URBs can fill their slot and cause -ENOSPC errors
even when all the lower-period slots are empty.

With the patch, if an URB doesn't fit in its assigned slot then the
scheduler will try using lower-period slots.  This will provide
greater flexibility.  As an example, the driver will be able to handle
more than just three or four mice, which the current driver cannot.

Signed-off-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 925dff5d

drivers/usb/host/uhci-q.c

+11 −6
Original line number Original line Diff line number Diff line
@@ -1065,13 +1065,18 @@ static int uhci_submit_interrupt(struct uhci_hcd *uhci, struct urb *urb, 
		}

		}

		if (exponent < 0)

		if (exponent < 0)

			return -EINVAL;

			return -EINVAL;



		/* If the slot is full, try a lower period */

		do {

			qh->period = 1 << exponent;

			qh->period = 1 << exponent;

			qh->skel = SKEL_INDEX(exponent);

			qh->skel = SKEL_INDEX(exponent);





			/* For now, interrupt phase is fixed by the layout

			/* For now, interrupt phase is fixed by the layout

		 * of the QH lists. */

			 * of the QH lists.

			 */

			qh->phase = (qh->period / 2) & (MAX_PHASE - 1);

			qh->phase = (qh->period / 2) & (MAX_PHASE - 1);

			ret = uhci_check_bandwidth(uhci, qh);

			ret = uhci_check_bandwidth(uhci, qh);

		} while (ret != 0 && --exponent >= 0);

		if (ret)

		if (ret)

			return ret;

			return ret;

	} else if (qh->period > urb->interval)

	} else if (qh->period > urb->interval)