mac80211: Check for queued frames before entering power save.

In a highly noisy environment, the tx rate of the driver drops and
the application slows down since it has not yet received ACKs for
the frames already queued in the hardware. Since this ACK may take
more than 100ms, stopping the dev queues for entering PS at this
stage breaks applications, WMM test cases in my testing.
If there are frames already pending in the tx queue, postponing the
PS logic helps to avoid redundant queue stops. When power save is
enabled by default and in a noisy environment, this API certainly
helps in improving the average throughput.

Signed-off-by: Vivek Natarajan <vnatarajan@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 965f1b16e53a..361bc5d85b1a 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -1819,6 +1819,9 @@ enum ieee80211_ampdu_mlme_action {
  * @set_ringparam: Set tx and rx ring sizes.
  *
  * @get_ringparam: Get tx and rx ring current and maximum sizes.
+ *
+ * @tx_frames_pending: Check if there is any pending frame in the hardware
+ *      queues before entering power save.
  */
 struct ieee80211_ops {
         void (*tx)(struct ieee80211_hw *hw, struct sk_buff *skb);
@@ -1906,6 +1909,7 @@ struct ieee80211_ops {
         int (*set_ringparam)(struct ieee80211_hw *hw, u32 tx, u32 rx);
         void (*get_ringparam)(struct ieee80211_hw *hw,
                               u32 *tx, u32 *tx_max, u32 *rx, u32 *rx_max);
+        bool (*tx_frames_pending)(struct ieee80211_hw *hw);
 };
 
 /**