2 files changed, 69 insertions, 7 deletions

diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index daa539a4287b..174dc1d7526b 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -1307,11 +1307,13 @@ enum ieee80211_ampdu_mlme_action {
  *
  * @hw_scan: Ask the hardware to service the scan request, no need to start
  *      the scan state machine in stack. The scan must honour the channel
- *      configuration done by the regulatory agent in the wiphy's registered
- *      bands. When the scan finishes, ieee80211_scan_completed() must be
- *      called; note that it also must be called when the scan cannot finish
- *      because the hardware is turned off! Anything else is a bug!
- *      Returns a negative error code which will be seen in userspace.
+ *      configuration done by the regulatory agent in the wiphy's
+ *      registered bands. The hardware (or the driver) needs to make sure
+ *      that power save is disabled. When the scan finishes,
+ *      ieee80211_scan_completed() must be called; note that it also must
+ *      be called when the scan cannot finish because the hardware is
+ *      turned off! Anything else is a bug! Returns a negative error code
+ *      which will be seen in userspace.
  *
  * @sw_scan_start: Notifier function that is called just before a software scan
  *      is started. Can be NULL, if the driver doesn't need this notification.
diff --git a/net/mac80211/scan.c b/net/mac80211/scan.c
index 46f35dc6accb..3bf9839f5916 100644
--- a/net/mac80211/scan.c
+++ b/net/mac80211/scan.c
@@ -214,6 +214,66 @@ void ieee80211_scan_failed(struct ieee80211_local *local)
         local->scan_req = NULL;
 }
 
+/*
+ * inform AP that we will go to sleep so that it will buffer the frames
+ * while we scan
+ */
+static void ieee80211_scan_ps_enable(struct ieee80211_sub_if_data *sdata)
+{
+        struct ieee80211_local *local = sdata->local;
+        bool ps = false;
+
+        /* FIXME: what to do when local->pspolling is true? */
+
+        del_timer_sync(&local->dynamic_ps_timer);
+        cancel_work_sync(&local->dynamic_ps_enable_work);
+
+        if (local->hw.conf.flags & IEEE80211_CONF_PS) {
+                ps = 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 power save was enabled, no need to send a nullfunc
+                 * frame because AP knows that we are sleeping. But if the
+                 * hardware is creating the nullfunc frame for power save
+                 * status (ie. IEEE80211_HW_PS_NULLFUNC_STACK is not
+                 * enabled) and power save was enabled, the firmware just
+                 * sent a null frame with power save disabled. So we need
+                 * to send a new nullfunc frame to inform the AP that we
+                 * are again sleeping.
+                 */
+                ieee80211_send_nullfunc(local, sdata, 1);
+}
+
+/* inform AP that we are awake again, unless power save is enabled */
+static void ieee80211_scan_ps_disable(struct ieee80211_sub_if_data *sdata)
+{
+        struct ieee80211_local *local = sdata->local;
+
+        if (!local->powersave)
+                ieee80211_send_nullfunc(local, sdata, 0);
+        else {
+                /*
+                 * In !IEEE80211_HW_PS_NULLFUNC_STACK case the hardware
+                 * will send a nullfunc frame with the powersave bit set
+                 * even though the AP already knows that we are sleeping.
+                 * This could be avoided by sending a null frame with power
+                 * save bit disabled before enabling the power save, but
+                 * this doesn't gain anything.
+                 *
+                 * When IEEE80211_HW_PS_NULLFUNC_STACK is enabled, no need
+                 * to send a nullfunc frame because AP already knows that
+                 * we are sleeping, let's just enable power save mode in
+                 * hardware.
+                 */
+                local->hw.conf.flags |= IEEE80211_CONF_PS;
+                ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
+        }
+}
+
 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
 {
         struct ieee80211_local *local = hw_to_local(hw);
@@ -268,7 +328,7 @@ void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
                 /* Tell AP we're back */
                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
                         if (sdata->u.mgd.flags & IEEE80211_STA_ASSOCIATED) {
-                                ieee80211_send_nullfunc(local, sdata, 0);
+                                ieee80211_scan_ps_disable(sdata);
                                 netif_tx_wake_all_queues(sdata->dev);
                         }
                 } else
@@ -441,7 +501,7 @@ int ieee80211_start_scan(struct ieee80211_sub_if_data *scan_sdata,
                 if (sdata->vif.type == NL80211_IFTYPE_STATION) {
                         if (sdata->u.mgd.flags & IEEE80211_STA_ASSOCIATED) {
                                 netif_tx_stop_all_queues(sdata->dev);
-                                ieee80211_send_nullfunc(local, sdata, 1);
+                                ieee80211_scan_ps_enable(sdata);
                         }
                 } else
                         netif_tx_stop_all_queues(sdata->dev);