iwlwifi: mvm: don't send identical PHY_CTXT_CMD

When we have an AP which supports HT and a single HT
station is connected, we change the min_width from
NL80211_CHAN_WIDTH_20_NOHT to NL80211_CHAN_WIDTH_20. This
of course has no implication on the channel width but still
sends a command to the firmware.
Remember the last width that was sent and refrain from
sending unnecessary commands to the firmware.

Sending a PHY_CTXT_CMD to the firmware has a cost since it
recalculates the presence on the medium and because of that
it closes the transmit queues for a short while.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>

drivers/net/wireless/intel/iwlwifi/mvm/mac80211.c

@@ -3406,10 +3406,24 @@ static void iwl_mvm_change_chanctx(struct ieee80211_hw *hw,
 		return;
 
 	mutex_lock(&mvm->mutex);
+
+	/* we are only changing the min_width, may be a noop */
+	if (changed == IEEE80211_CHANCTX_CHANGE_MIN_WIDTH) {
+		if (phy_ctxt->width == ctx->min_def.width)
+			goto out_unlock;
+
+		/* we are just toggling between 20_NOHT and 20 */
+		if (phy_ctxt->width <= NL80211_CHAN_WIDTH_20 &&
+		    ctx->min_def.width <= NL80211_CHAN_WIDTH_20)
+			goto out_unlock;
+	}
+
 	iwl_mvm_bt_coex_vif_change(mvm);
 	iwl_mvm_phy_ctxt_changed(mvm, phy_ctxt, &ctx->min_def,
 				 ctx->rx_chains_static,
 				 ctx->rx_chains_dynamic);
+
+out_unlock:
 	mutex_unlock(&mvm->mutex);
 }
 

drivers/net/wireless/intel/iwlwifi/mvm/mvm.h

@@ -147,6 +147,8 @@ struct iwl_mvm_phy_ctxt {
 	u16 color;
 	u32 ref;
 
+	enum nl80211_chan_width width;
+
 	/*
 	 * TODO: This should probably be removed. Currently here only for rate
 	 * scaling algorithm

drivers/net/wireless/intel/iwlwifi/mvm/phy-ctxt.c

@@ -272,6 +272,7 @@ int iwl_mvm_phy_ctxt_changed(struct iwl_mvm *mvm, struct iwl_mvm_phy_ctxt *ctxt,
 	}
 
 	ctxt->channel = chandef->chan;
+	ctxt->width = chandef->width;
 	return iwl_mvm_phy_ctxt_apply(mvm, ctxt, chandef,
 				      chains_static, chains_dynamic,
 				      action, 0);