USB: FHCI: upgrade the isochronous API

This patch attempts to fix the isochronous API in the fhci-hcd
driver.  There are two problems with the current code:

	ed->last_iso is used but not set anywhere.  The patch changes
	its name to ed->next_iso and uses it to store the frame number
	of the next available slot in the isochronous stream.

	urb->start_frame isn't set when the URB_ISO_ASAP flag is off.
	The patch sets it to the next available slot if the stream is
	in use, or the current frame otherwise.

This won't give the right behavior when an underrun occurs, but I
don't know enough about the driver to handle that case.

Unfortunately, I don't have any way to test these changes.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
CC: Anton Vorontsov <avorontsov@ru.mvista.com>
CC: Li Yang <leoli@freescale.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2 files changed, 7 insertions, 3 deletions

diff --git a/drivers/usb/host/fhci-sched.c b/drivers/usb/host/fhci-sched.c
index 8f18538e0ff7..95ca5986e672 100644
--- a/drivers/usb/host/fhci-sched.c
+++ b/drivers/usb/host/fhci-sched.c
@@ -739,9 +739,13 @@ void fhci_queue_urb(struct fhci_hcd *fhci, struct urb *urb)
         }
 
         /* for ISO transfer calculate start frame index */
-        if (ed->mode == FHCI_TF_ISO && urb->transfer_flags & URB_ISO_ASAP)
-                urb->start_frame = ed->td_head ? ed->last_iso + 1 :
+        if (ed->mode == FHCI_TF_ISO) {
+                /* Ignore the possibility of underruns */
+                urb->start_frame = ed->td_head ? ed->next_iso :
                                                  get_frame_num(fhci);
+                ed->next_iso = (urb->start_frame + urb->interval *
+                                urb->number_of_packets) & 0x07ff;
+        }
 
         /*
          * OHCI handles the DATA toggle itself,we just use the USB
diff --git a/drivers/usb/host/fhci.h b/drivers/usb/host/fhci.h
index 7cc1c32dc36c..154e6a007727 100644
--- a/drivers/usb/host/fhci.h
+++ b/drivers/usb/host/fhci.h
@@ -338,7 +338,7 @@ struct ed {
 
         /* read only parameters, should be cleared upon initialization */
         u8 toggle_carry;        /* toggle carry from the last TD submitted */
-        u32 last_iso;           /* time stamp of last queued ISO transfer */
+        u16 next_iso;           /* time stamp of next queued ISO transfer */
         struct td *td_head;     /* a pointer to the current TD handled */
 };