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OHCI: implement new semantics for URB_ISO_ASAP 

This patch (as1614) updates the isochronous scheduling in ohci-hcd to
match the new semantics for URB_ISO_ASAP.  Testing revealed a hardware
bug in the way my OHCI controller handles expired isochronous TDs;
consequently the patch tries hard to avoid creating them (unlike the
ehci-hcd and uhci-hcd drivers).

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Alan Stern 2012-10-01 10:32:15 -04:00 committed by Greg Kroah-Hartman
parent c44b225077
commit 6a41b4d3fe
2 changed files with 36 additions and 8 deletions
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40
drivers/usb/host/ohci-hcd.c
View File

@ -231,13 +231,41 @@ static int ohci_urb_enqueue (
frame &= ~(ed->interval - 1);
frame |= ed->branch;
urb->start_frame = frame;
/* yes, only URB_ISO_ASAP is supported, and
* urb->start_frame is never used as input.
*/
}
} else if (ed->type == PIPE_ISOCHRONOUS)
urb->start_frame = ed->last_iso + ed->interval;
} else if (ed->type == PIPE_ISOCHRONOUS) {
u16 next = ohci_frame_no(ohci) + 2;
u16 frame = ed->last_iso + ed->interval;
/* Behind the scheduling threshold? */
if (unlikely(tick_before(frame, next))) {
/* USB_ISO_ASAP: Round up to the first available slot */
if (urb->transfer_flags & URB_ISO_ASAP)
frame += (next - frame + ed->interval - 1) &
-ed->interval;
/*
* Not ASAP: Use the next slot in the stream. If
* the entire URB falls before the threshold, fail.
*/
else if (tick_before(frame + ed->interval *
(urb->number_of_packets - 1), next)) {
retval = -EXDEV;
usb_hcd_unlink_urb_from_ep(hcd, urb);
goto fail;
}
/*
* Some OHCI hardware doesn't handle late TDs
* correctly. After retiring them it proceeds to
* the next ED instead of the next TD. Therefore
* we have to omit the late TDs entirely.
*/
urb_priv->td_cnt = DIV_ROUND_UP(next - frame,
ed->interval);
}
urb->start_frame = frame;
}
/* fill the TDs and link them to the ed; and
* enable that part of the schedule, if needed

4
drivers/usb/host/ohci-q.c
View File

@ -596,7 +596,6 @@ static void td_submit_urb (
urb_priv->ed->hwHeadP &= ~cpu_to_hc32 (ohci, ED_C);
}
urb_priv->td_cnt = 0;
list_add (&urb_priv->pending, &ohci->pending);
if (data_len)
@ -672,7 +671,8 @@ static void td_submit_urb (
* we could often reduce the number of TDs here.
*/
case PIPE_ISOCHRONOUS:
for (cnt = 0; cnt < urb->number_of_packets; cnt++) {
for (cnt = urb_priv->td_cnt; cnt < urb->number_of_packets;
cnt++) {
int frame = urb->start_frame;
// FIXME scheduling should handle frame counter