rt2x00: rt2800pci: fix tx path by not accessing the skb after it was DMA mapped

rt2800pci used the callback write_tx_desc to write the tx descriptor but
also to update the txwi which is part of the dma mapped skb. Since the
memory was already DMA mapped _before_ the call to write_tx_desc the
device didn't get the txwi data at all or only sporadically.

The call order is basically as follows (from rt2x00queue.c):
1) write_tx_data
2) rt2x00queue_map_txskb
3) write_tx_desc

Hence, we shouldn't touch the skb in write_tx_desc anymore.

To fix this issue create a new rt2800pci_write_tx_data callback and use it
for updating the txwi _before_ the memory gets DMA mapped.

The tx descriptor is still written (as before) in write_tx_desc.

This patch allows basic TX on an rt305x soc device but I'm pretty sure
that it will fix pci based cards as well. I can associate just fine with
an AP now but I wasn't able to get a wpa secured connection working yet.

Signed-off-by: Helmut Schaa <helmut.schaa@googlemail.com>
Acked-by: Gertjan van Wingerde <gwingerde@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 27 insertions, 7 deletions

diff --git a/drivers/net/wireless/rt2x00/rt2800pci.c b/drivers/net/wireless/rt2x00/rt2800pci.c
index 2131f8f0c50..0e52f174896 100644
--- a/drivers/net/wireless/rt2x00/rt2800pci.c
+++ b/drivers/net/wireless/rt2x00/rt2800pci.c
@@ -613,15 +613,23 @@ static int rt2800pci_set_device_state(struct rt2x00_dev *rt2x00dev,
 /*
  * TX descriptor initialization
  */
-static void rt2800pci_write_tx_desc(struct rt2x00_dev *rt2x00dev,
-                                    struct sk_buff *skb,
-                                    struct txentry_desc *txdesc)
+static int rt2800pci_write_tx_data(struct queue_entry* entry,
+                                   struct txentry_desc *txdesc)
 {
-        struct skb_frame_desc *skbdesc = get_skb_frame_desc(skb);
-        __le32 *txd = skbdesc->desc;
-        __le32 *txwi = (__le32 *)(skb->data - rt2x00dev->ops->extra_tx_headroom);
+        struct rt2x00_dev *rt2x00dev = entry->queue->rt2x00dev;
+        struct sk_buff *skb = entry->skb;
+        struct skb_frame_desc *skbdesc;
+        int ret;
+        __le32 *txwi;
         u32 word;
 
+        ret = rt2x00pci_write_tx_data(entry, txdesc);
+        if (ret)
+                return ret;
+
+        skbdesc = get_skb_frame_desc(skb);
+        txwi = (__le32 *)(skb->data - rt2x00dev->ops->extra_tx_headroom);
+
         /*
          * Initialize TX Info descriptor
          */
@@ -670,6 +678,18 @@ static void rt2800pci_write_tx_desc(struct rt2x00_dev *rt2x00dev,
         _rt2x00_desc_write(txwi, 2, 0 /* skbdesc->iv[0] */);
         _rt2x00_desc_write(txwi, 3, 0 /* skbdesc->iv[1] */);
 
+        return 0;
+}
+
+
+static void rt2800pci_write_tx_desc(struct rt2x00_dev *rt2x00dev,
+                                    struct sk_buff *skb,
+                                    struct txentry_desc *txdesc)
+{
+        struct skb_frame_desc *skbdesc = get_skb_frame_desc(skb);
+        __le32 *txd = skbdesc->desc;
+        u32 word;
+
         /*
          * The buffers pointed by SD_PTR0/SD_LEN0 and SD_PTR1/SD_LEN1
          * must contains a TXWI structure + 802.11 header + padding + 802.11
@@ -1135,7 +1155,7 @@ static const struct rt2x00lib_ops rt2800pci_rt2x00_ops = {
         .reset_tuner            = rt2800_reset_tuner,
         .link_tuner             = rt2800_link_tuner,
         .write_tx_desc          = rt2800pci_write_tx_desc,
-        .write_tx_data          = rt2x00pci_write_tx_data,
+        .write_tx_data          = rt2800pci_write_tx_data,
         .write_beacon           = rt2800pci_write_beacon,
         .kick_tx_queue          = rt2800pci_kick_tx_queue,
         .kill_tx_queue          = rt2800pci_kill_tx_queue,