mac80211: Fix dynamic power save for scanning.

Not only ps_sdata but also IEEE80211_CONF_PS is to be considered
before restoring PS in scan_ps_disable(). For instance, when ps_sdata
is set but CONF_PS is not set just because the dynamic timer is still
running, a sw scan leads to setting of CONF_PS in scan_ps_disable
instead of restarting the dynamic PS timer.
Also for the above case, a null data frame is to be sent after
returning to operating channel which was not happening with the
current implementation. This patch fixes this too.

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

2 files changed, 17 insertions, 4 deletions

diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 419f186cfcf0..91dc8636d644 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -746,6 +746,7 @@ struct ieee80211_local {
         unsigned int wmm_acm; /* bit field of ACM bits (BIT(802.1D tag)) */
 
         bool pspolling;
+        bool scan_ps_enabled;
         /*
          * PS can only be enabled when we have exactly one managed
          * interface (and monitors) in PS, this then points there.
diff --git a/net/mac80211/scan.c b/net/mac80211/scan.c
index 4cf387c944bf..f1a4c7160300 100644
--- a/net/mac80211/scan.c
+++ b/net/mac80211/scan.c
@@ -227,7 +227,8 @@ static bool ieee80211_prep_hw_scan(struct ieee80211_local *local)
 static void ieee80211_scan_ps_enable(struct ieee80211_sub_if_data *sdata)
 {
         struct ieee80211_local *local = sdata->local;
-        bool ps = false;
+
+        local->scan_ps_enabled = false;
 
         /* FIXME: what to do when local->pspolling is true? */
 
@@ -235,12 +236,13 @@ static void ieee80211_scan_ps_enable(struct ieee80211_sub_if_data *sdata)
         cancel_work_sync(&local->dynamic_ps_enable_work);
 
         if (local->hw.conf.flags & IEEE80211_CONF_PS) {
-                ps = true;
+                local->scan_ps_enabled = true;
                 local->hw.conf.flags &= ~IEEE80211_CONF_PS;
                 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
         }
 
-        if (!ps || !(local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK))
+        if (!(local->scan_ps_enabled) ||
+            !(local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK))
                 /*
                  * If power save was enabled, no need to send a nullfunc
                  * frame because AP knows that we are sleeping. But if the
@@ -261,7 +263,7 @@ static void ieee80211_scan_ps_disable(struct ieee80211_sub_if_data *sdata)
 
         if (!local->ps_sdata)
                 ieee80211_send_nullfunc(local, sdata, 0);
-        else {
+        else if (local->scan_ps_enabled) {
                 /*
                  * In !IEEE80211_HW_PS_NULLFUNC_STACK case the hardware
                  * will send a nullfunc frame with the powersave bit set
@@ -277,6 +279,16 @@ static void ieee80211_scan_ps_disable(struct ieee80211_sub_if_data *sdata)
                  */
                 local->hw.conf.flags |= IEEE80211_CONF_PS;
                 ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
+        } else if (local->hw.conf.dynamic_ps_timeout > 0) {
+                /*
+                 * If IEEE80211_CONF_PS was not set and the dynamic_ps_timer
+                 * had been running before leaving the operating channel,
+                 * restart the timer now and send a nullfunc frame to inform
+                 * the AP that we are awake.
+                 */
+                ieee80211_send_nullfunc(local, sdata, 0);
+                mod_timer(&local->dynamic_ps_timer, jiffies +
+                          msecs_to_jiffies(local->hw.conf.dynamic_ps_timeout));
         }
 }