USB: IMX21: upgrade the isochronous API

This patch attempts to update the imx21-hcd driver to the current
standard for the isochronous API.  Firstly, urb->start_frame should
always be set by the driver; it is not an input parameter.  Secondly,
the URB_ISO_ASAP flag matters only when an URB is submitted to a
stream that has gotten an underrun.  It causes the URB to be scheduled
for the next available slot in the future, rather than the earliest
unused (and expired) slot.

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

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
CC: Sascha Hauer <kernel@pengutronix.de>
CC: Martin Fuzzey <mfuzzey@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/host/imx21-hcd.c b/drivers/usb/host/imx21-hcd.c
index f0ebe8e..03dc4d9 100644 (file)
--- a/drivers/usb/host/imx21-hcd.c
+++ b/drivers/usb/host/imx21-hcd.c
@@ -809,26 +809,36 @@ static int imx21_hc_urb_enqueue_isoc(struct usb_hcd *hcd,
 
        /* calculate frame */
        cur_frame = imx21_hc_get_frame(hcd);
-       if (urb->transfer_flags & URB_ISO_ASAP) {
-               if (list_empty(&ep_priv->td_list))
-                       urb->start_frame = cur_frame + 5;
-               else
-                       urb->start_frame = list_entry(
-                               ep_priv->td_list.prev,
-                               struct td, list)->frame + urb->interval;
-       }
-       urb->start_frame = wrap_frame(urb->start_frame);
-       if (frame_after(cur_frame, urb->start_frame)) {
-               dev_dbg(imx21->dev,
-                       "enqueue: adjusting iso start %d (cur=%d) asap=%d\n",
-                       urb->start_frame, cur_frame,
-                       (urb->transfer_flags & URB_ISO_ASAP) != 0);
-               urb->start_frame = wrap_frame(cur_frame + 1);
+       i = 0;
+       if (list_empty(&ep_priv->td_list)) {
+               urb->start_frame = wrap_frame(cur_frame + 5);
+       } else {
+               urb->start_frame = wrap_frame(list_entry(ep_priv->td_list.prev,
+                               struct td, list)->frame + urb->interval);
+
+               if (frame_after(cur_frame, urb->start_frame)) {
+                       dev_dbg(imx21->dev,
+                               "enqueue: adjusting iso start %d (cur=%d) asap=%d\n",
+                               urb->start_frame, cur_frame,
+                               (urb->transfer_flags & URB_ISO_ASAP) != 0);
+                       i = DIV_ROUND_UP(wrap_frame(
+                                       cur_frame - urb->start_frame),
+                                       urb->interval);
+                       if (urb->transfer_flags & URB_ISO_ASAP) {
+                               urb->start_frame = wrap_frame(urb->start_frame
+                                               + i * urb->interval);
+                               i = 0;
+                       } else if (i >= urb->number_of_packets) {
+                               ret = -EXDEV;
+                               goto alloc_dmem_failed;
+                       }
+               }
        }
 
        /* set up transfers */
+       urb_priv->isoc_remaining = urb->number_of_packets - i;
        td = urb_priv->isoc_td;
-       for (i = 0; i < urb->number_of_packets; i++, td++) {
+       for (; i < urb->number_of_packets; i++, td++) {
                unsigned int offset = urb->iso_frame_desc[i].offset;
                td->ep = ep;
                td->urb = urb;
@@ -840,7 +850,6 @@ static int imx21_hc_urb_enqueue_isoc(struct usb_hcd *hcd,
                list_add_tail(&td->list, &ep_priv->td_list);
        }
 
-       urb_priv->isoc_remaining = urb->number_of_packets;
        dev_vdbg(imx21->dev, "setup %d packets for iso frame %d->%d\n",
                urb->number_of_packets, urb->start_frame, td->frame);