rename lchan->rqd_ta to last_ta

Originally, the lchan stored only the Timing Advance from the initial
channel request, hence it was called rqd_ta.

Since quite a while now, rqd_ta also stores the most recent Timing
Advance from each received Measurement Report. So rename to last_ta.

This is cosmetic preparation for an upcoming patch that clarifies
whether the Timing Advance is already known for Channel Activation.

Change-Id: I1049526a173819baeb4978db5bf018ba3f1006a0

include/osmocom/bsc/gsm_data.h

@@ -657,7 +657,9 @@ struct gsm_lchan {
 		} ass_compl;
 	} abis_ip;
 
-	uint8_t rqd_ta;
+	/* At first, the Timing Advance from the initial Channel Request. Later, the Timing Advance value received from
+	 * the most recent Measurement Report. */
+	uint8_t last_ta;
 
 	/* table of neighbor cell measurements */
 	struct neigh_meas_proc neigh_meas[MAX_NEIGH_MEAS];

src/osmo-bsc/abis_rsl.c

@@ -541,7 +541,7 @@ int rsl_tx_chan_activ(struct gsm_lchan *lchan, uint8_t act_type, uint8_t ho_ref)
 		return rc;
 	}
 
-	ta = lchan->rqd_ta;
+	ta = lchan->last_ta;
 
 	/* BS11 requires TA shifted by 2 bits */
 	if (bts->type == GSM_BTS_TYPE_BS11)
@@ -1147,8 +1147,8 @@ static int rsl_rx_meas_res(struct msgb *msg)
 		if (msg->lchan->ts->trx->bts->type == GSM_BTS_TYPE_BS11
 		 || msg->lchan->ts->trx->bts->type == GSM_BTS_TYPE_NOKIA_SITE)
 			mr->ms_l1.ta >>= 2;
-		/* store TA for next assignment/handover */
-		mr->lchan->rqd_ta = mr->ms_l1.ta;
+		/* store TA for handover decision, and for intra-cell re-assignment */
+		mr->lchan->last_ta = mr->ms_l1.ta;
 	}
 	if (TLVP_PRESENT(&tp, RSL_IE_L3_INFO)) {
 		msg->l3h = (uint8_t *) TLVP_VAL(&tp, RSL_IE_L3_INFO);
@@ -1756,7 +1756,7 @@ void abis_rsl_chan_rqd_queue_poll(struct gsm_bts *bts)
 	OSMO_ASSERT(lchan->rqd_ref);
 
 	*(lchan->rqd_ref) = rqd->ref;
-	lchan->rqd_ta = rqd->ta;
+	lchan->last_ta = rqd->ta;
 
 	LOG_LCHAN(lchan, LOGL_DEBUG, "MS: Channel Request: reason=%s ra=0x%02x ta=%d\n",
 		  gsm_chreq_name(rqd->reason), rqd->ref.ra, rqd->ta);
@@ -1788,7 +1788,7 @@ int rsl_tx_imm_assignment(struct gsm_lchan *lchan)
 
 	/* use request reference extracted from CHAN_RQD */
 	memcpy(&ia->req_ref, lchan->rqd_ref, sizeof(ia->req_ref));
-	ia->timing_advance = lchan->rqd_ta;
+	ia->timing_advance = lchan->last_ta;
 	if (!lchan->ts->hopping.enabled) {
 		ia->mob_alloc_len = 0;
 	} else {

src/osmo-bsc/handover_decision_2.c

@@ -1543,10 +1543,10 @@ static void on_measurement_report(struct gsm_meas_rep *mr)
 
 	/* Max Distance */
 	if (lchan->meas_rep_count > 0
-	    && lchan->rqd_ta > ho_get_hodec2_max_distance(bts->ho)) {
+	    && lchan->last_ta > ho_get_hodec2_max_distance(bts->ho)) {
 		global_ho_reason = HO_REASON_MAX_DISTANCE;
 		LOGPHOLCHAN(lchan, LOGL_NOTICE, "TA is TOO HIGH: %u > %d\n",
-			    lchan->rqd_ta, ho_get_hodec2_max_distance(bts->ho));
+			    lchan->last_ta, ho_get_hodec2_max_distance(bts->ho));
 		/* start penalty timer to prevent coming back too
 		 * early. it must be started before selecting a better cell,
 		 * so there is no assignment selected, due to running

src/osmo-bsc/lchan_fsm.c

@@ -580,7 +580,7 @@ static void lchan_fsm_wait_ts_ready_onenter(struct osmo_fsm_inst *fi, uint32_t p
 		ms_power_dbm = ms_pwr_dbm(bts->band, old_lchan->ms_power);
 		lchan_update_ms_power_ctrl_level(lchan, ms_power_dbm >= 0 ? ms_power_dbm : bts->ms_max_power);
 		lchan->bs_power = old_lchan->bs_power;
-		lchan->rqd_ta = old_lchan->rqd_ta;
+		lchan->last_ta = old_lchan->last_ta;
 	} else {
 		lchan_update_ms_power_ctrl_level(lchan, bts->ms_max_power);
 		/* Upon last entering the UNUSED state, from lchan_reset():

src/osmo-bsc/lcs_loc_req.c

@@ -313,7 +313,7 @@ static void lcs_loc_req_wait_loc_resp_onenter(struct osmo_fsm_inst *fi, uint32_t
 		plr.bssmap_le.perform_loc_req.apdu = (struct bsslap_pdu){
 			.msg_type = BSSLAP_MSGT_TA_LAYER3,
 			.ta_layer3 = {
-				.ta = lchan->rqd_ta,
+				.ta = lchan->last_ta,
 			},
 		};
 	} else {
@@ -365,7 +365,7 @@ static void lcs_loc_req_handover_performed(struct lcs_loc_req *lcs_loc_req)
 			.msg_type = BSSLAP_MSGT_RESET,
 			.reset = {
 				.cell_id = lchan->ts->trx->bts->cell_identity,
-				.ta = lchan->rqd_ta,
+				.ta = lchan->last_ta,
 				.cause = BSSLAP_CAUSE_INTRA_BSS_HO,
 			},
 		};

src/osmo-bsc/lcs_ta_req.c

@@ -210,7 +210,7 @@ void lcs_ta_req_got_ta_onenter(struct osmo_fsm_inst *fi, uint32_t prev_state)
 					.msg_type = BSSLAP_MSGT_TA_RESPONSE,
 					.ta_response = {
 						.cell_id = lchan->ts->trx->bts->cell_identity,
-						.ta = lchan->rqd_ta,
+						.ta = lchan->last_ta,
 					},
 				},
 			},