mac80211: inform the driver about update of dtim_period

Currently, when the driver requires the DTIM period,
mac80211 will wait to hear a beacon before association.
This behavior is suboptimal since some drivers may be
able to deal with knowing the DTIM period after the
association, if they get it at all.

To address this, notify the drivers with bss_info_changed
with the new BSS_CHANGED_DTIM_PERIOD flag when the DTIM
becomes known. This might be when changing to associated,
or later when the entire association was done with only
probe response information.

Rename the hardware flag for the current behaviour to
IEEE80211_HW_NEED_DTIM_BEFORE_ASSOC to more accurately
reflect its behaviour. IEEE80211_HW_NEED_DTIM_PERIOD is
no longer accurate as all drivers get the DTIM period
now, just not before association.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 9 insertions, 7 deletions

diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 7a27e00c513a..398b6ca4a9c5 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -208,6 +208,8 @@ struct ieee80211_chanctx_conf {
  * @BSS_CHANGED_TXPOWER: TX power setting changed for this interface
  * @BSS_CHANGED_P2P_PS: P2P powersave settings (CTWindow, opportunistic PS)
  *      changed (currently only in P2P client mode, GO mode will be later)
+ * @BSS_CHANGED_DTIM_PERIOD: the DTIM period value was changed (set when
+ *      it becomes valid, managed mode only)
  */
 enum ieee80211_bss_change {
         BSS_CHANGED_ASSOC               = 1<<0,
@@ -230,6 +232,7 @@ enum ieee80211_bss_change {
         BSS_CHANGED_PS                  = 1<<17,
         BSS_CHANGED_TXPOWER             = 1<<18,
         BSS_CHANGED_P2P_PS              = 1<<19,
+        BSS_CHANGED_DTIM_PERIOD         = 1<<20,
 
         /* when adding here, make sure to change ieee80211_reconfig */
 };
@@ -271,9 +274,8 @@ enum ieee80211_rssi_event {
  *      if the hardware cannot handle this it must set the
  *      IEEE80211_HW_2GHZ_SHORT_SLOT_INCAPABLE hardware flag
  * @dtim_period: num of beacons before the next DTIM, for beaconing,
- *      valid in station mode only while @assoc is true and if also
- *      requested by %IEEE80211_HW_NEED_DTIM_PERIOD (cf. also hw conf
- *      @ps_dtim_period)
+ *      valid in station mode only if after the driver was notified
+ *      with the %BSS_CHANGED_DTIM_PERIOD flag, will be non-zero then.
  * @sync_tsf: last beacon's/probe response's TSF timestamp (could be old
  *      as it may have been received during scanning long ago)
  * @sync_device_ts: the device timestamp corresponding to the sync_tsf,
@@ -1328,9 +1330,9 @@ struct ieee80211_tx_control {
  *      When this flag is set, signaling beacon-loss will cause an immediate
  *      change to disassociated state.
  *
- * @IEEE80211_HW_NEED_DTIM_PERIOD:
- *      This device needs to know the DTIM period for the BSS before
- *      associating.
+ * @IEEE80211_HW_NEED_DTIM_BEFORE_ASSOC:
+ *      This device needs to get data from beacon before association (i.e.
+ *      dtim_period).
  *
  * @IEEE80211_HW_SUPPORTS_PER_STA_GTK: The device's crypto engine supports
  *      per-station GTKs as used by IBSS RSN or during fast transition. If
@@ -1375,7 +1377,7 @@ enum ieee80211_hw_flags {
         IEEE80211_HW_2GHZ_SHORT_PREAMBLE_INCAPABLE      = 1<<4,
         IEEE80211_HW_SIGNAL_UNSPEC                      = 1<<5,
         IEEE80211_HW_SIGNAL_DBM                         = 1<<6,
-        IEEE80211_HW_NEED_DTIM_PERIOD                   = 1<<7,
+        IEEE80211_HW_NEED_DTIM_BEFORE_ASSOC             = 1<<7,
         IEEE80211_HW_SPECTRUM_MGMT                      = 1<<8,
         IEEE80211_HW_AMPDU_AGGREGATION                  = 1<<9,
         IEEE80211_HW_SUPPORTS_PS                        = 1<<10,