EHCI: implement new semantics for URB_ISO_ASAP

This patch (as1612) updates the isochronous scheduling and processing
in ehci-hcd to match the new semantics for URB_ISO_ASAP.  It also adds
a missing "unlikely" in sitd_complete() to match the corresponding
statement in itd_complete(), and it increments urb->error_count in a
couple of places that had been overlooked.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 26 insertions, 7 deletions

diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c
index e08e65d8e004..b538a4d62d5e 100644
--- a/drivers/usb/host/ehci-sched.c
+++ b/drivers/usb/host/ehci-sched.c
@@ -1386,8 +1386,8 @@ iso_stream_schedule (
 
         /* Typical case: reuse current schedule, stream is still active.
          * Hopefully there are no gaps from the host falling behind
-         * (irq delays etc), but if there are we'll take the next
-         * slot in the schedule, implicitly assuming URB_ISO_ASAP.
+         * (irq delays etc).  If there are, the behavior depends on
+         * whether URB_ISO_ASAP is set.
          */
         if (likely (!list_empty (&stream->td_list))) {
 
@@ -1414,9 +1414,25 @@ iso_stream_schedule (
                         goto fail;
                 }
 
-                /* Behind the scheduling threshold?  Assume URB_ISO_ASAP. */
-                if (unlikely(start < next))
-                        start += (next - start + period - 1) & (- period);
+                /* Behind the scheduling threshold? */
+                if (unlikely(start < next)) {
+
+                        /* USB_ISO_ASAP: Round up to the first available slot */
+                        if (urb->transfer_flags & URB_ISO_ASAP)
+                                start += (next - start + period - 1) & -period;
+
+                        /*
+                         * Not ASAP: Use the next slot in the stream.  If
+                         * the entire URB falls before the threshold, fail.
+                         */
+                        else if (start + span - period < next) {
+                                ehci_dbg(ehci, "iso urb late %p (%u+%u < %u)\n",
+                                                urb, start + base,
+                                                span - period, next + base);
+                                status = -EXDEV;
+                                goto fail;
+                        }
+                }
 
                 start += base;
         }
@@ -1699,7 +1715,7 @@ static bool itd_complete(struct ehci_hcd *ehci, struct ehci_itd *itd)
                         urb->actual_length += desc->actual_length;
                 } else {
                         /* URB was too late */
-                        desc->status = -EXDEV;
+                        urb->error_count++;
                 }
         }
 
@@ -2072,7 +2088,7 @@ static bool sitd_complete(struct ehci_hcd *ehci, struct ehci_sitd *sitd)
         t = hc32_to_cpup(ehci, &sitd->hw_results);
 
         /* report transfer status */
-        if (t & SITD_ERRS) {
+        if (unlikely(t & SITD_ERRS)) {
                 urb->error_count++;
                 if (t & SITD_STS_DBE)
                         desc->status = usb_pipein (urb->pipe)
@@ -2082,6 +2098,9 @@ static bool sitd_complete(struct ehci_hcd *ehci, struct ehci_sitd *sitd)
                         desc->status = -EOVERFLOW;
                 else /* XACT, MMF, etc */
                         desc->status = -EPROTO;
+        } else if (unlikely(t & SITD_STS_ACTIVE)) {
+                /* URB was too late */
+                urb->error_count++;
         } else {
                 desc->status = 0;
                 desc->actual_length = desc->length - SITD_LENGTH(t);