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>
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@ -1065,13 +1065,18 @@ static int uhci_submit_interrupt(struct uhci_hcd *uhci, struct urb *urb,
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}
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if (exponent < 0)
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return -EINVAL;
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qh->period = 1 << exponent;
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qh->skel = SKEL_INDEX(exponent);
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/* For now, interrupt phase is fixed by the layout
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* of the QH lists. */
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qh->phase = (qh->period / 2) & (MAX_PHASE - 1);
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ret = uhci_check_bandwidth(uhci, qh);
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/* If the slot is full, try a lower period */
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do {
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qh->period = 1 << exponent;
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qh->skel = SKEL_INDEX(exponent);
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/* For now, interrupt phase is fixed by the layout
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* of the QH lists.
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*/
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qh->phase = (qh->period / 2) & (MAX_PHASE - 1);
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ret = uhci_check_bandwidth(uhci, qh);
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} while (ret != 0 && --exponent >= 0);
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if (ret)
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return ret;
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} else if (qh->period > urb->interval)
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