rt2x00: Properly request tx headroom for alignment operations.

Current rt2x00 drivers may result in a "ieee80211_tx_status: headroom too
small" error message when a frame needs to be properly aligned before
transmitting it.
This is because the space needed to ensure proper alignment isn't
requested from mac80211.
Fix this by adding sufficient amount of alignment space to the amount
of headroom requested for TX frames.

Reported-by: David Ellingsworth <david@identd.dyndns.org>
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, 11 insertions, 1 deletions

diff --git a/drivers/net/wireless/rt2x00/rt2x00dev.c b/drivers/net/wireless/rt2x00/rt2x00dev.c
index 06c43ca39bf8..265e66dba552 100644
--- a/drivers/net/wireless/rt2x00/rt2x00dev.c
+++ b/drivers/net/wireless/rt2x00/rt2x00dev.c
@@ -686,7 +686,17 @@ static int rt2x00lib_probe_hw(struct rt2x00_dev *rt2x00dev)
         /*
          * Initialize extra TX headroom required.
          */
-        rt2x00dev->hw->extra_tx_headroom = rt2x00dev->ops->extra_tx_headroom;
+        rt2x00dev->hw->extra_tx_headroom =
+                max_t(unsigned int, IEEE80211_TX_STATUS_HEADROOM,
+                      rt2x00dev->ops->extra_tx_headroom);
+
+        /*
+         * Take TX headroom required for alignment into account.
+         */
+        if (test_bit(DRIVER_REQUIRE_L2PAD, &rt2x00dev->flags))
+                rt2x00dev->hw->extra_tx_headroom += RT2X00_L2PAD_SIZE;
+        else if (test_bit(DRIVER_REQUIRE_DMA, &rt2x00dev->flags))
+                rt2x00dev->hw->extra_tx_headroom += RT2X00_ALIGN_SIZE;
 
         /*
          * Register HW.