iwlwifi: mvm: Disable uAPSD for a DCM client

A binding object associates virtual MACs to a Phy.
Binding object can ask (and get) air time, thus
allowing several MACs to share the medium.
A binding object can be in either one of 3 states:
1) standalone - A single active MAC
2) Different Channel Mode (DCM) - There are 2 active
   MACs or more (not necessarily just clients), but each
   has its own channel.
3) Same Channel Mode (SCM) - There are 2 active
   MACs or more (not necessarily just clients), that
   share the same channel.
This patch introduces an additional condition for enabling uAPSD:
uAPSD should be disabled for a client in DCM.
The reason for that is a low latency issue in Miracast.

Signed-off-by: Avri Altman <avri.altman@intel.com>
Reviewed-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>

drivers/net/wireless/iwlwifi/mvm/power.c

@@ -268,10 +268,30 @@ static void iwl_mvm_power_configure_uapsd(struct iwl_mvm *mvm,
 		IWL_MVM_PS_HEAVY_RX_THLD_PERCENT;
 }
 
+static void iwl_mvm_binding_iterator(void *_data, u8 *mac,
+				      struct ieee80211_vif *vif)
+{
+	unsigned long *data = _data;
+	struct iwl_mvm_vif *mvmvif = iwl_mvm_vif_from_mac80211(vif);
+
+	if (!mvmvif->phy_ctxt)
+		return;
+
+	if (vif->type == NL80211_IFTYPE_STATION ||
+	    vif->type == NL80211_IFTYPE_AP)
+		__set_bit(mvmvif->phy_ctxt->id, data);
+}
+
 static bool iwl_mvm_power_allow_uapsd(struct iwl_mvm *mvm,
 				       struct ieee80211_vif *vif)
 {
 	struct iwl_mvm_vif *mvmvif = iwl_mvm_vif_from_mac80211(vif);
+	unsigned long phy_ctxt_counter = 0;
+
+	ieee80211_iterate_active_interfaces_atomic(mvm->hw,
+						   IEEE80211_IFACE_ITER_NORMAL,
+						   iwl_mvm_binding_iterator,
+						   &phy_ctxt_counter);
 
 	if (!memcmp(mvmvif->uapsd_misbehaving_bssid, vif->bss_conf.bssid,
 		    ETH_ALEN))
@@ -289,6 +309,13 @@ static bool iwl_mvm_power_allow_uapsd(struct iwl_mvm *mvm,
 	    IEEE80211_P2P_OPPPS_ENABLE_BIT))
 		return false;
 
+	/*
+	 * Avoid using uAPSD if client is in DCM -
+	 * low latency issue in Miracast
+	 */
+	if (hweight8(phy_ctxt_counter) >= 2)
+		return false;
+
 	return true;
 }