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[068/104] USB: UHCI: accept very late isochronous URBs

Message ID 1381419752-29733-69-git-send-email-kamal@canonical.com
State New
Headers show

Commit Message

Kamal Mostafa Oct. 10, 2013, 3:41 p.m. UTC 
3.8.13.11 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Alan Stern <stern@rowland.harvard.edu>

commit bef073b067a7b1874a6b381e0035bb0516d71a77 upstream.

Commit 24f531371de1 (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 c44b225077bb (UHCI: implement
new semantics for URB_ISO_ASAP).

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
 drivers/usb/host/uhci-q.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)
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Patch

diff --git a/drivers/usb/host/uhci-q.c b/drivers/usb/host/uhci-q.c
index 3b08519..3232578 100644
--- 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);
 		}
 	}