USB: UHCI: accept very late isochronous URBs

Commit 4a77405f60f9 (USB: EHCI: accept very late isochronous URBs)
changed the isochronous API provided by ehci-hcd.  URBs submitted too
late, so that the time slots for all their packets have already
expired, are no longer rejected outright.  Instead the submission is
accepted, and the URB completes normally with a -EXDEV error for each
packet.  This is what client drivers expect.

This patch implements the same policy in uhci-hcd.  It should be
applied to all kernels containing commit e263b33348f5 (UHCI: implement
new semantics for URB_ISO_ASAP).

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

diff --git a/drivers/usb/host/uhci-q.c b/drivers/usb/host/uhci-q.c
index 041c6ddb695c8ec6fa17d371fe7904de2e47d5ab..da6f56d996ce56f61cd1be20a093c2c16ff54702 100644 (file)
--- a/drivers/usb/host/uhci-q.c
+++ b/drivers/usb/host/uhci-q.c
@@ -1303,7 +1303,7 @@ static int uhci_submit_isochronous(struct uhci_hcd *uhci, struct urb *urb,
                }
 
                /* Fell behind? */
-               if (uhci_frame_before_eq(frame, next)) {
+               if (!uhci_frame_before_eq(next, frame)) {
 
                        /* USB_ISO_ASAP: Round up to the first available slot */
                        if (urb->transfer_flags & URB_ISO_ASAP)
@@ -1311,13 +1311,17 @@ static int uhci_submit_isochronous(struct uhci_hcd *uhci, struct urb *urb,
                                                -qh->period;
 
                        /*
-                        * Not ASAP: Use the next slot in the stream.  If
-                        * the entire URB falls before the threshold, fail.
+                        * Not ASAP: Use the next slot in the stream,
+                        * no matter what.
                         */
                        else if (!uhci_frame_before_eq(next,
                                        frame + (urb->number_of_packets - 1) *
                                                qh->period))
-                               return -EXDEV;
+                               dev_dbg(uhci_dev(uhci), "iso underrun %p (%u+%u < %u)\n",
+                                               urb, frame,
+                                               (urb->number_of_packets - 1) *
+                                                       qh->period,
+                                               next);
                }
        }