Gitweb: http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=e58dce...
Commit: e58dcebcd83b5902411e747ee7807219dee6bcf2
Parent: 925dff5dee04fb46d2e67c088c54b331f97672ee
Author: Alan Stern <stern@rowland.harvard.edu>
AuthorDate: Thu Sep 25 16:59:57 2008 -0400
Committer: Greg Kroah-Hartman <gregkh@suse.de>
CommitDate: Fri Oct 17 14:41:01 2008 -0700
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 <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
drivers/usb/host/uhci-q.c | 17 +++++++++++------
1 files changed, 11 insertions(+), 6 deletions(-)
diff --git a/drivers/usb/host/uhci-q.c b/drivers/usb/host/uhci-q.c
index 1f0c2cf..5631d89 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)
--
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