rt2x00: Re-order tx descriptor writing code in drivers.

Where possible, write the tx descriptor words from start to end, to
follow a logical ordering of words.
Where this is not possible (in rt2400pci, rt2500pci and rt61pci) add
a comment as to why word 0 needs to be written last.

Signed-off-by: Gertjan van Wingerde <gwingerde@gmail.com>
Acked-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/drivers/net/wireless/rt2x00/rt61pci.c b/drivers/net/wireless/rt2x00/rt61pci.c
index 99c298100fb6..55aa010aeee2 100644
--- a/drivers/net/wireless/rt2x00/rt61pci.c
+++ b/drivers/net/wireless/rt2x00/rt61pci.c
@@ -1813,6 +1813,11 @@ static void rt61pci_write_tx_desc(struct rt2x00_dev *rt2x00dev,
                 rt2x00_desc_write(txd, 11, word);
         }
 
+        /*
+         * Writing TXD word 0 must the last to prevent a race condition with
+         * the device, whereby the device may take hold of the TXD before we
+         * finished updating it.
+         */
         rt2x00_desc_read(txd, 0, &word);
         rt2x00_set_field32(&word, TXD_W0_OWNER_NIC, 1);
         rt2x00_set_field32(&word, TXD_W0_VALID, 1);