mac80211: use ps-poll when dynamic power save mode is disabled

When a directed tim bit is set, mac80211 currently disables power save
ands sends a null frame to the AP. But if dynamic power save is
disabled, mac80211 will not enable power save ever gain. Fix this by
adding ps-poll functionality to mac80211. When a directed tim bit is
set, mac80211 sends a ps-poll frame to the AP and checks for the more
data bit in the returned data frames.

Using ps-poll is slower than waking up with null frame, but it's saves more
power in cases where the traffic is low. Userspace can control if either
ps-poll or null wakeup method is used by enabling and disabling dynamic
power save.

Signed-off-by: Kalle Valo <kalle.valo@nokia.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 34 insertions, 0 deletions

diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 8e8ddbfcd236..0e030d3fbdec 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -731,6 +731,39 @@ ieee80211_rx_h_decrypt(struct ieee80211_rx_data *rx)
         return result;
 }
 
+static ieee80211_rx_result debug_noinline
+ieee80211_rx_h_check_more_data(struct ieee80211_rx_data *rx)
+{
+        struct ieee80211_local *local;
+        struct ieee80211_hdr *hdr;
+        struct sk_buff *skb;
+
+        local = rx->local;
+        skb = rx->skb;
+        hdr = (struct ieee80211_hdr *) skb->data;
+
+        if (!local->pspolling)
+                return RX_CONTINUE;
+
+        if (!ieee80211_has_fromds(hdr->frame_control))
+                /* this is not from AP */
+                return RX_CONTINUE;
+
+        if (!ieee80211_is_data(hdr->frame_control))
+                return RX_CONTINUE;
+
+        if (!ieee80211_has_moredata(hdr->frame_control)) {
+                /* AP has no more frames buffered for us */
+                local->pspolling = false;
+                return RX_CONTINUE;
+        }
+
+        /* more data bit is set, let's request a new frame from the AP */
+        ieee80211_send_pspoll(local, rx->sdata);
+
+        return RX_CONTINUE;
+}
+
 static void ap_sta_ps_start(struct sta_info *sta)
 {
         struct ieee80211_sub_if_data *sdata = sta->sdata;
@@ -1987,6 +2020,7 @@ static void ieee80211_invoke_rx_handlers(struct ieee80211_sub_if_data *sdata,
         CALL_RXH(ieee80211_rx_h_passive_scan)
         CALL_RXH(ieee80211_rx_h_check)
         CALL_RXH(ieee80211_rx_h_decrypt)
+        CALL_RXH(ieee80211_rx_h_check_more_data)
         CALL_RXH(ieee80211_rx_h_sta_process)
         CALL_RXH(ieee80211_rx_h_defragment)
         CALL_RXH(ieee80211_rx_h_ps_poll)