rt2x00: Split watchdog check into a DMA and STATUS timeout

The watchdog for rt2800usb triggers frequently causing all URB's
to be canceled often enough to interrupt the normal TX flow.
More research indicated that not the URB upload to the USB host
were hanging, but instead the TX status reports.

To correctly detect what is going on, we introduce Q_INDEX_DMA_DONE
which is an index counter between Q_INDEX_DONE and Q_INDEX and indicates
if the frame has been transfered to the device.

This also requires the rt2x00queue timeout functions to be updated
to differentiate between a DMA timeout (time between Q_INDEX and
Q_INDEX_DMA_DONE timeout) and a STATUS timeout (time between
Q_INDEX_DMA_DONE and Q_INDEX_DONE timeout)

All Q_INDEX_DMA_DONE code was taken from the RFC from
Helmut Schaa <helmut.schaa@googlemail.com> for the implementation
for watchdog for rt2800pci.

Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Acked-by: Gertjan van Wingerde <gwingerde@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/rt2x00/rt2x00.h b/drivers/net/wireless/rt2x00/rt2x00.h
index 762f6b4..0ae942c 100644
--- a/drivers/net/wireless/rt2x00/rt2x00.h
+++ b/drivers/net/wireless/rt2x00/rt2x00.h
@@ -1070,6 +1070,7 @@
  */
 void rt2x00lib_beacondone(struct rt2x00_dev *rt2x00dev);
 void rt2x00lib_pretbtt(struct rt2x00_dev *rt2x00dev);
+void rt2x00lib_dmadone(struct queue_entry *entry);
 void rt2x00lib_txdone(struct queue_entry *entry,
 		      struct txdone_entry_desc *txdesc);
 void rt2x00lib_txdone_noinfo(struct queue_entry *entry, u32 status);