mac80211: disable powersave if pm_qos asks for low latency

When an application asks for a latency lower than the beacon interval
there's nothing we can do -- we need to stay awake and not have the
AP buffer frames for us. Add code to automatically calculate this
constraint in mac80211 so drivers need not concern themselves with it.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 32 insertions, 4 deletions

diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index 06d9a1d23252..c39a214e7ad0 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -17,6 +17,7 @@
 #include <linux/if_arp.h>
 #include <linux/etherdevice.h>
 #include <linux/rtnetlink.h>
+#include <linux/pm_qos_params.h>
 #include <net/mac80211.h>
 #include <asm/unaligned.h>
 
@@ -515,7 +516,7 @@ static void ieee80211_change_ps(struct ieee80211_local *local)
 }
 
 /* need to hold RTNL or interface lock */
-void ieee80211_recalc_ps(struct ieee80211_local *local)
+void ieee80211_recalc_ps(struct ieee80211_local *local, s32 latency)
 {
         struct ieee80211_sub_if_data *sdata, *found = NULL;
         int count = 0;
@@ -534,10 +535,22 @@ void ieee80211_recalc_ps(struct ieee80211_local *local)
                 count++;
         }
 
-        if (count == 1 && found->u.mgd.powersave)
-                local->ps_sdata = found;
-        else
+        if (count == 1 && found->u.mgd.powersave) {
+                s32 beaconint_us;
+
+                if (latency < 0)
+                        latency = pm_qos_requirement(PM_QOS_NETWORK_LATENCY);
+
+                beaconint_us = ieee80211_tu_to_usec(
+                                        found->vif.bss_conf.beacon_int);
+
+                if (beaconint_us > latency)
+                        local->ps_sdata = NULL;
+                else
+                        local->ps_sdata = found;
+        } else {
                 local->ps_sdata = NULL;
+        }
 
         ieee80211_change_ps(local);
 }
@@ -2324,3 +2337,18 @@ void ieee80211_mlme_notify_scan_completed(struct ieee80211_local *local)
                 ieee80211_restart_sta_timer(sdata);
         rcu_read_unlock();
 }
+
+int ieee80211_max_network_latency(struct notifier_block *nb,
+                                  unsigned long data, void *dummy)
+{
+        s32 latency_usec = (s32) data;
+        struct ieee80211_local *local =
+                container_of(nb, struct ieee80211_local,
+                             network_latency_notifier);
+
+        mutex_lock(&local->iflist_mtx);
+        ieee80211_recalc_ps(local, latency_usec);
+        mutex_unlock(&local->iflist_mtx);
+
+        return 0;
+}