This patch (as1613) updates the isochronous scheduling in uhci-hcd to
match the new semantics for URB_ISO_ASAP. The amount of code
alteration is smaller than it looks because of a change in the
indentation level.
Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
---
drivers/usb/host/uhci-q.c | 73 ++++++++++++++++++++++------------------------
1 file changed, 36 insertions(+), 37 deletions(-)
Index: usb-3.6/drivers/usb/host/uhci-q.c
===================================================================
--- usb-3.6.orig/drivers/usb/host/uhci-q.c
+++ usb-3.6/drivers/usb/host/uhci-q.c
@@ -1256,7 +1256,8 @@ static int uhci_submit_isochronous(struc
struct uhci_qh *qh)
{
struct uhci_td *td = NULL; /* Since urb->number_of_packets > 0 */
- int i, frame;
+ int i;
+ unsigned frame, next;
unsigned long destination, status;
struct urb_priv *urbp = (struct urb_priv *) urb->hcpriv;
@@ -1265,37 +1266,29 @@ static int uhci_submit_isochronous(struc
urb->number_of_packets >= UHCI_NUMFRAMES)
return -EFBIG;
+ uhci_get_current_frame_number(uhci);
+
/* Check the period and figure out the starting frame number */
if (!qh->bandwidth_reserved) {
qh->period = urb->interval;
- if (urb->transfer_flags & URB_ISO_ASAP) {
- qh->phase = -1; /* Find the best phase */
- i = uhci_check_bandwidth(uhci, qh);
- if (i)
- return i;
-
- /* Allow a little time to allocate the TDs */
- uhci_get_current_frame_number(uhci);
- frame = uhci->frame_number + 10;
-
- /* Move forward to the first frame having the
- * correct phase */
- urb->start_frame = frame + ((qh->phase - frame) &
- (qh->period - 1));
- } else {
- i = urb->start_frame - uhci->last_iso_frame;
- if (i <= 0 || i >= UHCI_NUMFRAMES)
- return -EINVAL;
- qh->phase = urb->start_frame & (qh->period - 1);
- i = uhci_check_bandwidth(uhci, qh);
- if (i)
- return i;
- }
+ qh->phase = -1; /* Find the best phase */
+ i = uhci_check_bandwidth(uhci, qh);
+ if (i)
+ return i;
+
+ /* Allow a little time to allocate the TDs */
+ next = uhci->frame_number + 10;
+ frame = qh->phase;
+
+ /* Round up to the first available slot */
+ frame += (next - frame + qh->period - 1) & -qh->period;
} else if (qh->period != urb->interval) {
return -EINVAL; /* Can't change the period */
} else {
+ next = uhci->frame_number + 2;
+
/* Find the next unused frame */
if (list_empty(&qh->queue)) {
frame = qh->iso_frame;
@@ -1308,25 +1301,31 @@ static int uhci_submit_isochronous(struc
lurb->number_of_packets *
lurb->interval;
}
- if (urb->transfer_flags & URB_ISO_ASAP) {
- /* Skip some frames if necessary to insure
- * the start frame is in the future.
+
+ /* Fell behind? */
+ if (uhci_frame_before_eq(frame, next)) {
+
+ /* USB_ISO_ASAP: Round up to the first available slot */
+ if (urb->transfer_flags & URB_ISO_ASAP)
+ frame += (next - frame + qh->period - 1) &
+ -qh->period;
+
+ /*
+ * Not ASAP: Use the next slot in the stream. If
+ * the entire URB falls before the threshold, fail.
*/
- uhci_get_current_frame_number(uhci);
- if (uhci_frame_before_eq(frame, uhci->frame_number)) {
- frame = uhci->frame_number + 1;
- frame += ((qh->phase - frame) &
- (qh->period - 1));
- }
- } /* Otherwise pick up where the last URB leaves off */
- urb->start_frame = frame;
+ else if (!uhci_frame_before_eq(next,
+ frame + (urb->number_of_packets - 1) *
+ qh->period))
+ return -EXDEV;
+ }
}
/* Make sure we won't have to go too far into the future */
if (uhci_frame_before_eq(uhci->last_iso_frame + UHCI_NUMFRAMES,
- urb->start_frame + urb->number_of_packets *
- urb->interval))
+ frame + urb->number_of_packets * urb->interval))
return -EFBIG;
+ urb->start_frame = frame;
status = TD_CTRL_ACTIVE | TD_CTRL_IOS;
destination = (urb->pipe & PIPE_DEVEP_MASK) | usb_packetid(urb->pipe);
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