From: Alan Stern Date: Thu, 25 Sep 2008 20:59:57 +0000 (-0400) Subject: USB: UHCI: improve scheduling of interrupt URBs X-Git-Tag: v2.6.28-rc1~254^2~43 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=e58dcebcd83b5902411e747ee7807219dee6bcf2;p=platform%2Fkernel%2Flinux-stable.git 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: Alan Stern Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/usb/host/uhci-q.c b/drivers/usb/host/uhci-q.c index 1f0c2cf26e5d..5631d89c8730 100644 --- a/drivers/usb/host/uhci-q.c +++ b/drivers/usb/host/uhci-q.c @@ -1065,13 +1065,18 @@ static int uhci_submit_interrupt(struct uhci_hcd *uhci, struct urb *urb, } if (exponent < 0) return -EINVAL; - qh->period = 1 << exponent; - qh->skel = SKEL_INDEX(exponent); - /* For now, interrupt phase is fixed by the layout - * of the QH lists. */ - qh->phase = (qh->period / 2) & (MAX_PHASE - 1); - ret = uhci_check_bandwidth(uhci, qh); + /* If the slot is full, try a lower period */ + do { + qh->period = 1 << exponent; + qh->skel = SKEL_INDEX(exponent); + + /* For now, interrupt phase is fixed by the layout + * of the QH lists. + */ + qh->phase = (qh->period / 2) & (MAX_PHASE - 1); + ret = uhci_check_bandwidth(uhci, qh); + } while (ret != 0 && --exponent >= 0); if (ret) return ret; } else if (qh->period > urb->interval)