iwlwifi: support truly passive scanning

If passive scanning is requested we should not ask the
microcode to do active scanning after detecting traffic
on a channel -- that should only be used when an active
scan is requested but some channels are marked passive.
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

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

@@ -712,7 +712,12 @@ static void iwl_bg_request_scan(struct work_struct *data)
 	} else if (priv->scan_bands & BIT(IEEE80211_BAND_5GHZ)) {
 		band = IEEE80211_BAND_5GHZ;
 		rate = IWL_RATE_6M_PLCP;
-		scan->good_CRC_th = IWL_GOOD_CRC_TH;
+		/*
+		 * If active scaning is requested but a certain channel
+		 * is marked passive, we can do active scanning if we
+		 * detect transmissions.
+		 */
+		scan->good_CRC_th = is_active ? IWL_GOOD_CRC_TH : 0;
 
 		/* Force use of chains B and C (0x6) for scan Rx for 4965
 		 * Avoid A (0x1) because of its off-channel reception on A-band.

drivers/net/wireless/iwlwifi/iwl3945-base.c

@@ -3078,7 +3078,12 @@ static void iwl3945_bg_request_scan(struct work_struct *data)
 		band = IEEE80211_BAND_2GHZ;
 	} else if (priv->scan_bands & BIT(IEEE80211_BAND_5GHZ)) {
 		scan->tx_cmd.rate = IWL_RATE_6M_PLCP;
-		scan->good_CRC_th = IWL_GOOD_CRC_TH;
+		/*
+		 * If active scaning is requested but a certain channel
+		 * is marked passive, we can do active scanning if we
+		 * detect transmissions.
+		 */
+		scan->good_CRC_th = is_active ? IWL_GOOD_CRC_TH : 0;
 		band = IEEE80211_BAND_5GHZ;
 	} else {
 		IWL_WARN(priv, "Invalid scan band count\n");