On Sun, 24 Mar 2002, Johannes Erdfelt wrote:
> There's a slight bug in your fixed code. len will always be 0 at the end
> of the previous loop, so your check will always incorrectly add the last
> zero packet.
Right. Just realized this when I saw the irda-usb still sending zero
packets at the wrong place. Seems my thinko was I've mixed up len-=pktsze
with maxsze (IIRC it was formerly) and thought len would become <0 except
for the case where we want to add the zero packet :(
> Does this patch work correctly?
Looks like you've changed the code so my thinko would become right now.
Haven't tested yet but will do tonight - and AFAICS it should be ok.
Meanwhile I'm appending what I've done just now to solve the problem. It
is already tested and made irda-usb now completely happy with uhci.
I think it's up to you to select which one you prefer.
Martin
----------------------------------
--- linux-2.5.7/drivers/usb/uhci.c Sun Mar 10 03:45:21 2002
+++ v2.5.7-md/drivers/usb/uhci.c Mon Mar 25 08:21:22 2002
@@ -1223,6 +1223,7 @@
unsigned long destination, status;
struct uhci *uhci = (struct uhci *)urb->dev->bus->hcpriv;
int maxsze = usb_maxpacket(urb->dev, urb->pipe, usb_pipeout(urb->pipe));
+ int pktsze;
int len = urb->transfer_buffer_length;
struct urb_priv *urbp = (struct urb_priv *)urb->hcpriv;
dma_addr_t data = urbp->transfer_buffer_dma_handle;
@@ -1247,7 +1248,7 @@
* Build the DATA TD's
*/
do { /* Allow zero length packets */
- int pktsze = len;
+ pktsze = len;
if (pktsze > maxsze)
pktsze = maxsze;
@@ -1270,14 +1271,20 @@
usb_pipeout(urb->pipe));
} while (len > 0);
- if (usb_pipeout(urb->pipe) && (urb->transfer_flags & USB_ZERO_PACKET) &&
- urb->transfer_buffer_length) {
+ /* USB_ZERO_PACKET means adding a 0-length packet, if
+ * direction is OUT and the transfer_length was an
+ * exact multiple of maxsze, hence pktsze==maxsze for
+ * last non-zero packet - which also excludes the case
+ * where transfer_buffer_length==0 (already handled above)
+ */
+ if ((urb->transfer_flags&USB_ZERO_PACKET) && usb_pipeout(urb->pipe)
+ && pktsze==maxsze) {
td = uhci_alloc_td(uhci, urb->dev);
if (!td)
return -ENOMEM;
uhci_add_td_to_urb(urb, td);
- uhci_fill_td(td, status, destination | UHCI_NULL_DATA_SIZE |
+ uhci_fill_td(td, status, destination | (UHCI_NULL_DATA_SIZE<<21) |
(usb_gettoggle(urb->dev, usb_pipeendpoint(urb->pipe),
usb_pipeout(urb->pipe)) << TD_TOKEN_TOGGLE),
data);
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