qcacmn: update average rssi in scan entry

If elapsed time since last rssi update for a particular
scan entry is smaller than a thresold, calculate a
running average of the RSSI values. Otherwise last RSSI
is more representive of the signal strength.

Change-Id: I4cbecc8b6bfbb73c272544114b063b25c26e14fe
CRs-Fixed: 1095299

umac/scan/core/src/wlan_scan_cache_db.c

@@ -364,12 +364,11 @@ static void scm_delete_duplicate_entry(struct scan_dbs *scan_db,
 	struct scan_cache_node *scan_node)
 {
 	struct scan_cache_entry *scan_entry;
+	uint64_t time_gap;
 
 	scan_entry = scan_node->entry;
 	/* If old entry have the ssid but new entry does not */
 	if (!scan_params->ssid.length && scan_entry->ssid.length) {
-		uint64_t time_gap;
-
 		/*
 		 * New entry has a hidden SSID and old one has the SSID.
 		 * Add the entry by using the ssid of the old entry
@@ -397,9 +396,29 @@ static void scm_delete_duplicate_entry(struct scan_dbs *scan_db,
 	 */
 	if (scan_params->channel_mismatch) {
 		scan_params->rssi_raw = scan_entry->rssi_raw;
+		scan_params->avg_rssi = scan_entry->avg_rssi;
 		scan_params->rssi_timestamp =
 			scan_entry->rssi_timestamp;
+	} else {
+		/* If elapsed time since last rssi update for this
+		 * entry is smaller than a thresold, calculate a
+		 * running average of the RSSI values.
+		 * Otherwise last RSSI is more representive of the
+		 * signal strength.
+		 */
+		time_gap =
+			scan_entry->rssi_timestamp -
+			scan_params->rssi_timestamp;
+		if (time_gap > WLAN_RSSI_AVERAGING_TIME)
+			scan_params->avg_rssi =
+				WLAN_RSSI_IN(scan_params->rssi_raw);
+		else
+			WLAN_RSSI_LPF(scan_params->avg_rssi,
+					scan_params->rssi_raw);
+
+		scan_params->rssi_timestamp = scan_params->scan_entry_time;
 	}
+
 	/* copy wsn ie from scan_entry to scan_params*/
 	scm_update_alt_wcn_ie(scan_entry, scan_params);
 
@@ -542,6 +561,7 @@ QDF_STATUS scm_handle_bcn_probe(struct scheduler_msg *msg)
 		goto free_nbuf;
 	}
 
+
 	scm_info("Received %s from BSSID: %pM tsf_delta = %u Seq Num: %x ssid:%.*s",
 		(bcn->frm_type == MGMT_SUBTYPE_PROBE_RESP) ?
 		"Probe Rsp" : "Beacon", scan_entry->bssid.bytes,

umac/scan/dispatcher/inc/wlan_scan_public_structs.h

@@ -247,7 +247,7 @@ struct scan_cache_entry {
 	struct wlan_ssid ssid;
 	uint16_t seq_num;
 	enum wlan_phymode phy_mode;
-	int8_t avg_rssi;
+	int32_t avg_rssi;
 	int8_t rssi_raw;
 	uint16_t bcn_int;
 	union wlan_capability cap_info;

umac/scan/dispatcher/inc/wlan_scan_utils_api.h

@@ -181,6 +181,7 @@ util_scan_entry_reset_timestamp(struct scan_cache_entry *scan_entry)
 /*
  * Macros used for RSSI calculation.
  */
+#define WLAN_RSSI_AVERAGING_TIME (5 * 1000) /* 5 seconds */
 
 #define WLAN_RSSI_EP_MULTIPLIER (1<<7)  /* pow2 to optimize out * and / */
 

umac/scan/dispatcher/src/wlan_scan_utils_api.c

@@ -575,6 +575,7 @@ util_scan_unpack_beacon_frame(uint8_t *frame,
 		(le16toh(*(uint16_t *)hdr->i_seq) >> WLAN_SEQ_SEQ_SHIFT);
 
 	scan_entry->rssi_raw = rx_param->rssi;
+	scan_entry->avg_rssi = WLAN_RSSI_DUMMY_MARKER;
 	scan_entry->tsf_delta = rx_param->tsf_delta;
 
 	/* store jiffies */
@@ -593,10 +594,8 @@ util_scan_unpack_beacon_frame(uint8_t *frame,
 		bcn->timestamp, 8);
 	scan_entry->erp = ERP_NON_ERP_PRESENT;
 
-
-	scan_entry->rssi_timestamp =
-		scan_entry->scan_entry_time =
-			qdf_mc_timer_get_system_time();
+	scan_entry->scan_entry_time =
+		qdf_mc_timer_get_system_time();
 
 	scan_entry->raw_frame.len = frame_len;
 	qdf_mem_copy(scan_entry->raw_frame.ptr,