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>

1 files changed, 26 insertions, 17 deletions

diff --git a/drivers/usb/host/imx21-hcd.c b/drivers/usb/host/imx21-hcd.c
index f0ebe8e7c58b..03dc4d9cbeca 100644
--- 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);