UHCI: short control URBs get a status stage

It has recently been pointed out that short control transfers should
have a status stage, even if they generate an error because
URB_SHORT_NOT_OK was set.  This patch (as935) changes uhci-hcd to
enable the status stage when this happens.

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

1 files changed, 38 insertions, 21 deletions

diff --git a/drivers/usb/host/uhci-q.c b/drivers/usb/host/uhci-q.c
index 4aed305982ec..3bb908ca38e9 100644
--- a/drivers/usb/host/uhci-q.c
+++ b/drivers/usb/host/uhci-q.c
@@ -827,8 +827,10 @@ static int uhci_submit_control(struct uhci_hcd *uhci, struct urb *urb,
          * If direction is "send", change the packet ID from SETUP (0x2D)
          * to OUT (0xE1).  Else change it from SETUP to IN (0x69) and
          * set Short Packet Detect (SPD) for all data packets.
+         *
+         * 0-length transfers always get treated as "send".
          */
-        if (usb_pipeout(urb->pipe))
+        if (usb_pipeout(urb->pipe) || len == 0)
                 destination ^= (USB_PID_SETUP ^ USB_PID_OUT);
         else {
                 destination ^= (USB_PID_SETUP ^ USB_PID_IN);
@@ -839,7 +841,12 @@ static int uhci_submit_control(struct uhci_hcd *uhci, struct urb *urb,
          * Build the DATA TDs
          */
         while (len > 0) {
-                int pktsze = min(len, maxsze);
+                int pktsze = maxsze;
+
+                if (len <= pktsze) {            /* The last data packet */
+                        pktsze = len;
+                        status &= ~TD_CTRL_SPD;
+                }
 
                 td = uhci_alloc_td(uhci);
                 if (!td)
@@ -866,20 +873,10 @@ static int uhci_submit_control(struct uhci_hcd *uhci, struct urb *urb,
                 goto nomem;
         *plink = LINK_TO_TD(td);
 
-        /*
-         * It's IN if the pipe is an output pipe or we're not expecting
-         * data back.
-         */
-        destination &= ~TD_TOKEN_PID_MASK;
-        if (usb_pipeout(urb->pipe) || !urb->transfer_buffer_length)
-                destination |= USB_PID_IN;
-        else
-                destination |= USB_PID_OUT;
-
+        /* Change direction for the status transaction */
+        destination ^= (USB_PID_IN ^ USB_PID_OUT);
         destination |= TD_TOKEN_TOGGLE;         /* End in Data1 */
 
-        status &= ~TD_CTRL_SPD;
-
         uhci_add_td_to_urbp(td, urbp);
         uhci_fill_td(td, status | TD_CTRL_IOC,
                         destination | uhci_explen(0), 0);
@@ -1185,10 +1182,18 @@ static int uhci_result_common(struct uhci_hcd *uhci, struct urb *urb)
                                 }
                         }
 
+                /* Did we receive a short packet? */
                 } else if (len < uhci_expected_length(td_token(td))) {
 
-                        /* We received a short packet */
-                        if (urb->transfer_flags & URB_SHORT_NOT_OK)
+                        /* For control transfers, go to the status TD if
+                         * this isn't already the last data TD */
+                        if (qh->type == USB_ENDPOINT_XFER_CONTROL) {
+                                if (td->list.next != urbp->td_list.prev)
+                                        ret = 1;
+                        }
+
+                        /* For bulk and interrupt, this may be an error */
+                        else if (urb->transfer_flags & URB_SHORT_NOT_OK)
                                 ret = -EREMOTEIO;
 
                         /* Fixup needed only if this isn't the URB's last TD */
@@ -1208,10 +1213,6 @@ static int uhci_result_common(struct uhci_hcd *uhci, struct urb *urb)
 
 err:
         if (ret < 0) {
-                /* In case a control transfer gets an error
-                 * during the setup stage */
-                urb->actual_length = max(urb->actual_length, 0);
-
                 /* Note that the queue has stopped and save
                  * the next toggle value */
                 qh->element = UHCI_PTR_TERM;
@@ -1489,9 +1490,25 @@ __acquires(uhci->lock)
 {
         struct urb_priv *urbp = (struct urb_priv *) urb->hcpriv;
 
+        if (qh->type == USB_ENDPOINT_XFER_CONTROL) {
+
+                /* urb->actual_length < 0 means the setup transaction didn't
+                 * complete successfully.  Either it failed or the URB was
+                 * unlinked first.  Regardless, don't confuse people with a
+                 * negative length. */
+                urb->actual_length = max(urb->actual_length, 0);
+
+                /* Report erroneous short transfers */
+                if (unlikely((urb->transfer_flags & URB_SHORT_NOT_OK) &&
+                                urb->actual_length <
+                                        urb->transfer_buffer_length &&
+                                urb->status == 0))
+                        urb->status = -EREMOTEIO;
+        }
+
         /* When giving back the first URB in an Isochronous queue,
          * reinitialize the QH's iso-related members for the next URB. */
-        if (qh->type == USB_ENDPOINT_XFER_ISOC &&
+        else if (qh->type == USB_ENDPOINT_XFER_ISOC &&
                         urbp->node.prev == &qh->queue &&
                         urbp->node.next != &qh->queue) {
                 struct urb *nurb = list_entry(urbp->node.next,