UHCI: no dummy TDs for Iso QHs

Isochronous queues don't need a dummy TD because the Queue Header
isn't managed by the hardware.  This patch (as836) removes the
unnecessary dummy TDs.

The patch also fixes a long-standing typo in a comment (a "don't" was
missing -- potentially very confusing!).

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

2 files changed, 11 insertions, 8 deletions

diff --git a/drivers/usb/host/uhci-debug.c b/drivers/usb/host/uhci-debug.c
index b40bc1ac9b8c..3fbb5ba80249 100644
--- a/drivers/usb/host/uhci-debug.c
+++ b/drivers/usb/host/uhci-debug.c
@@ -208,7 +208,7 @@ static int uhci_show_qh(struct uhci_qh *qh, char *buf, int len, int space)
                                         space, "", nurbs);
         }
 
-        if (qh->udev) {
+        if (qh->dummy_td) {
                 out += sprintf(out, "%*s  Dummy TD\n", space, "");
                 out += uhci_show_td(qh->dummy_td, out, len - (out - buf), 0);
         }
diff --git a/drivers/usb/host/uhci-q.c b/drivers/usb/host/uhci-q.c
index 30b88459ac7d..5afcc5227284 100644
--- a/drivers/usb/host/uhci-q.c
+++ b/drivers/usb/host/uhci-q.c
@@ -248,16 +248,18 @@ static struct uhci_qh *uhci_alloc_qh(struct uhci_hcd *uhci,
         INIT_LIST_HEAD(&qh->node);
 
         if (udev) {             /* Normal QH */
-                qh->dummy_td = uhci_alloc_td(uhci);
-                if (!qh->dummy_td) {
-                        dma_pool_free(uhci->qh_pool, qh, dma_handle);
-                        return NULL;
+                qh->type = hep->desc.bmAttributes & USB_ENDPOINT_XFERTYPE_MASK;
+                if (qh->type != USB_ENDPOINT_XFER_ISOC) {
+                        qh->dummy_td = uhci_alloc_td(uhci);
+                        if (!qh->dummy_td) {
+                                dma_pool_free(uhci->qh_pool, qh, dma_handle);
+                                return NULL;
+                        }
                 }
                 qh->state = QH_STATE_IDLE;
                 qh->hep = hep;
                 qh->udev = udev;
                 hep->hcpriv = qh;
-                qh->type = hep->desc.bmAttributes & USB_ENDPOINT_XFERTYPE_MASK;
 
         } else {                /* Skeleton QH */
                 qh->state = QH_STATE_ACTIVE;
@@ -275,7 +277,8 @@ static void uhci_free_qh(struct uhci_hcd *uhci, struct uhci_qh *qh)
         list_del(&qh->node);
         if (qh->udev) {
                 qh->hep->hcpriv = NULL;
-                uhci_free_td(uhci, qh->dummy_td);
+                if (qh->dummy_td)
+                        uhci_free_td(uhci, qh->dummy_td);
         }
         dma_pool_free(uhci->qh_pool, qh, qh->dma_handle);
 }
@@ -327,7 +330,7 @@ static int uhci_cleanup_queue(struct uhci_hcd *uhci, struct uhci_qh *qh,
                 goto done;
         qh->element = UHCI_PTR_TERM;
 
-        /* Control pipes have to worry about toggles */
+        /* Control pipes don't have to worry about toggles */
         if (qh->type == USB_ENDPOINT_XFER_CONTROL)
                 goto done;