iwlwifi: replace minimum slot time constant

There are a number of places where the minimum
slot time is hardcoded to 20 TU, add a new
constant for that and use it everywhere.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>

drivers/net/wireless/iwlwifi/iwl-agn-hcmd.c

@@ -308,7 +308,7 @@ static int iwlagn_set_pan_params(struct iwl_priv *priv)
 	if (priv->_agn.hw_roc_channel) {
 		/* both contexts must be used for this to happen */
 		slot1 = priv->_agn.hw_roc_duration;
-		slot0 = 20;
+		slot0 = IWL_MIN_SLOT_TIME;
 	} else if (ctx_bss->vif && ctx_pan->vif) {
 		int bcnint = ctx_pan->vif->bss_conf.beacon_int;
 		int dtim = ctx_pan->vif->bss_conf.dtim_period ?: 1;
@@ -334,12 +334,12 @@ static int iwlagn_set_pan_params(struct iwl_priv *priv)
 		if (test_bit(STATUS_SCAN_HW, &priv->status) ||
 		    (!ctx_bss->vif->bss_conf.idle &&
 		     !ctx_bss->vif->bss_conf.assoc)) {
-			slot0 = dtim * bcnint * 3 - 20;
-			slot1 = 20;
+			slot0 = dtim * bcnint * 3 - IWL_MIN_SLOT_TIME;
+			slot1 = IWL_MIN_SLOT_TIME;
 		} else if (!ctx_pan->vif->bss_conf.idle &&
 			   !ctx_pan->vif->bss_conf.assoc) {
-			slot1 = bcnint * 3 - 20;
-			slot0 = 20;
+			slot1 = bcnint * 3 - IWL_MIN_SLOT_TIME;
+			slot0 = IWL_MIN_SLOT_TIME;
 		}
 	} else if (ctx_pan->vif) {
 		slot0 = 0;
@@ -348,8 +348,8 @@ static int iwlagn_set_pan_params(struct iwl_priv *priv)
 		slot1 = max_t(int, DEFAULT_BEACON_INTERVAL, slot1);
 
 		if (test_bit(STATUS_SCAN_HW, &priv->status)) {
-			slot0 = slot1 * 3 - 20;
-			slot1 = 20;
+			slot0 = slot1 * 3 - IWL_MIN_SLOT_TIME;
+			slot1 = IWL_MIN_SLOT_TIME;
 		}
 	}
 

drivers/net/wireless/iwlwifi/iwl-agn.c

@@ -3792,7 +3792,7 @@ static int iwl_mac_remain_on_channel(struct ieee80211_hw *hw,
 	queue_delayed_work(priv->workqueue, &priv->_agn.hw_roc_work,
 			   msecs_to_jiffies(duration + 20));
 
-	msleep(20);
+	msleep(IWL_MIN_SLOT_TIME); /* TU is almost ms */
 	ieee80211_ready_on_channel(priv->hw);
 
  out:

drivers/net/wireless/iwlwifi/iwl-commands.h

@@ -4370,6 +4370,11 @@ int iwl_agn_check_rxon_cmd(struct iwl_priv *priv);
  * REPLY_WIPAN_PARAMS = 0xb2 (Commands and Notification)
  */
 
+/*
+ * Minimum slot time in TU
+ */
+#define IWL_MIN_SLOT_TIME	20
+
 /**
  * struct iwl_wipan_slot
  * @width: Time in TU