On Mon, 26 Aug 2013 14:50:53 -0400 (EDT)
Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote:
> This patch does the real work. It fixes up ehci-hcd so that an URB
> submitted by a completion handler will keep the isochronous stream
> alive, even if the handler was delayed by running in a tasklet and the
> queue has emptied out.
>
> As I mentioned earlier, this is not a simple change.
>
> Alan Stern
>
>
>
> drivers/usb/host/ehci-sched.c | 164 +++++++++++++++++++++++++-----------------
> drivers/usb/host/ehci.h | 1
> 2 files changed, 101 insertions(+), 64 deletions(-)
Below is the approach I proposed(mentioned in another thread), which should be
simper than this one, any comments?
drivers/usb/host/ehci-sched.c | 53 ++++++++++++++++++++++++++++++++++++++---
drivers/usb/host/ehci.h | 1 +
2 files changed, 51 insertions(+), 3 deletions(-)
diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c
index 83be03f..80ef95d 100644
--- a/drivers/usb/host/ehci-sched.c
+++ b/drivers/usb/host/ehci-sched.c
@@ -1370,6 +1370,33 @@ sitd_slot_ok (
return 1;
}
+/* rebase in case of underun without ISO_ASAP together */
+static int iso_stream_rebase(struct ehci_hcd *ehci, struct urb *urb,
+ struct ehci_iso_stream *stream, u32 span, u32 period)
+{
+ u32 i, end;
+ u32 mod = ehci->periodic_size;
+
+ if (ehci->last_base == -1)
+ return 0;
+
+ end = ((stream->next_uframe + span - period) >> 3) & (mod - 1);
+ for (i = ehci->last_base; i != ehci->last_iso_frame;
+ i = (i + 1) & (mod - 1)) {
+ /* don't schedule URB which is behind base totally */
+ if (end == i) {
+ for (i = 0; i < urb->number_of_packets; i++) {
+ urb->iso_frame_desc[i].length = 0;
+ urb->iso_frame_desc[i].status = 0;
+ }
+ return 1;
+ }
+ if (((stream->next_uframe >> 3) & (mod - 1)) == i)
+ ehci->last_iso_frame = i;
+ }
+ return 0;
+}
+
/*
* This scheduler plans almost as far into the future as it has actual
* periodic schedule slots. (Affected by TUNE_FLS, which defaults to
@@ -1409,7 +1436,9 @@ iso_stream_schedule (
* (irq delays etc). If there are, the behavior depends on
* whether URB_ISO_ASAP is set.
*/
- if (likely (!list_empty (&stream->td_list))) {
+ if (likely (!list_empty (&stream->td_list) ||
+ hcd_complete_in_progress(
+ ehci_to_hcd(ehci), urb))) {
/* Take the isochronous scheduling threshold into account */
if (ehci->i_thresh)
@@ -1417,6 +1446,14 @@ iso_stream_schedule (
else
next = (now + 2 + 7) & ~0x07; /* full frame cache */
+ if (list_empty(&stream->td_list) &&
+ !(urb->transfer_flags & URB_ISO_ASAP))
+ if (iso_stream_rebase(ehci, urb, stream, span,
+ period)) {
+ status = 1;
+ goto fail;
+ }
+
/*
* Use ehci->last_iso_frame as the base. There can't be any
* TDs scheduled for earlier than that.
@@ -1517,6 +1554,7 @@ iso_stream_schedule (
/* Make sure scan_isoc() sees these */
if (ehci->isoc_count == 0)
ehci->last_iso_frame = now >> 3;
+ ehci->last_base = -1;
return 0;
fail:
@@ -1838,7 +1876,10 @@ static int itd_submit (struct ehci_hcd *ehci, struct urb *urb,
status = iso_stream_schedule(ehci, urb, stream);
if (likely (status == 0))
itd_link_urb (ehci, urb, ehci->periodic_size << 3, stream);
- else
+ else if (status > 0) {
+ ehci_urb_done(ehci, urb, 0);
+ status = 0;
+ } else
usb_hcd_unlink_urb_from_ep(ehci_to_hcd(ehci), urb);
done_not_linked:
spin_unlock_irqrestore (&ehci->lock, flags);
@@ -2224,7 +2265,10 @@ static int sitd_submit (struct ehci_hcd *ehci, struct urb *urb,
status = iso_stream_schedule(ehci, urb, stream);
if (status == 0)
sitd_link_urb (ehci, urb, ehci->periodic_size << 3, stream);
- else
+ else if (status > 0) {
+ ehci_urb_done(ehci, urb, 0);
+ status = 0;
+ } else
usb_hcd_unlink_urb_from_ep(ehci_to_hcd(ehci), urb);
done_not_linked:
spin_unlock_irqrestore (&ehci->lock, flags);
@@ -2255,6 +2299,9 @@ static void scan_isoc(struct ehci_hcd *ehci)
}
ehci->now_frame = now_frame;
+ if (ehci->last_base == -1)
+ ehci->last_base = ehci->last_iso_frame;
+
frame = ehci->last_iso_frame;
for (;;) {
union ehci_shadow q, *q_p;
diff --git a/drivers/usb/host/ehci.h b/drivers/usb/host/ehci.h
index 2822e79..279e182 100644
--- a/drivers/usb/host/ehci.h
+++ b/drivers/usb/host/ehci.h
@@ -149,6 +149,7 @@ struct ehci_hcd { /* one per controller */
unsigned intr_unlink_wait_cycle;
unsigned intr_unlink_cycle;
unsigned now_frame; /* frame from HC hardware */
+ unsigned last_base; /* previous 'last_iso_frame' */
unsigned last_iso_frame; /* last frame scanned for iso */
unsigned intr_count; /* intr activity count */
unsigned isoc_count; /* isoc activity count */
Thanks,
--
Ming Lei
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