Change in osmo-pcu[master]: pcuif: Submit data_req with len=0 as idle frames

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pespin gerrit-no-reply at lists.osmocom.org
Wed Sep 22 14:00:38 UTC 2021


pespin has uploaded this change for review. ( https://gerrit.osmocom.org/c/osmo-pcu/+/25535 )


Change subject: pcuif: Submit data_req with len=0 as idle frames
......................................................................

pcuif: Submit data_req with len=0 as idle frames

This way PCU always answers DATA.ind and the BTS can still clearly
identify idle frames. It also simplifies testing and verification of
correct behavior.

Related: SYS#4919
Change-Id: Ife718eeed2af011479c03099ea109518f04567bc
---
M src/gprs_rlcmac_sched.cpp
M src/pcu_l1_if.cpp
2 files changed, 30 insertions(+), 7 deletions(-)



  git pull ssh://gerrit.osmocom.org:29418/osmo-pcu refs/changes/35/25535/1

diff --git a/src/gprs_rlcmac_sched.cpp b/src/gprs_rlcmac_sched.cpp
index 405b7db..b3639fb 100644
--- a/src/gprs_rlcmac_sched.cpp
+++ b/src/gprs_rlcmac_sched.cpp
@@ -486,9 +486,9 @@
 	}
 	/* Prio 3: send dummy control message if need to poll or USF */
 	else {
-		/* If there's no TBF attached to this PDCH, we can early skip
-		 * since there's nothing to transmit nor to poll/USF. This way
-		 * we help BTS energy saving (on TRX!=C0) by sending nothing
+		/* If there's no TBF attached to this PDCH, we can submit an empty
+		 * data_req since there's nothing to transmit nor to poll/USF. This
+		 * way we help BTS energy saving (on TRX!=C0) by sending nothing
 		 * instead of a dummy block. The early return is done here and
 		 * not at the start of the function because the condition below
 		 * (num_tbfs==0) may not be enough, because temporary dummy TBFs
@@ -504,8 +504,11 @@
 		 * TRX0, since BTS is not preparing dummy bursts on idle TS for us */
 		skip_idle = skip_idle && trx != 0;
 #endif
-		if (skip_idle)
-			return 0;
+		if (skip_idle) {
+			msg = NULL; /* submit empty frame */
+			goto tx_pdtch;
+		}
+
 		if ((msg = sched_dummy())) {
 			/* increase counter */
 			gsmtap_cat = PCU_GSMTAP_C_DL_DUMMY;
@@ -535,6 +538,7 @@
 	tap_n_acc(msg, bts, trx, ts, fn, gsmtap_cat);
 
 	/* send PDTCH/PACCH to L1 */
+tx_pdtch:
 	pcu_l1if_tx_pdtch(msg, bts, trx, ts, bts->trx[trx].arfcn, fn, block_nr);
 
 	return 0;
diff --git a/src/pcu_l1_if.cpp b/src/pcu_l1_if.cpp
index 1600da0..8d9defc 100644
--- a/src/pcu_l1_if.cpp
+++ b/src/pcu_l1_if.cpp
@@ -212,7 +212,8 @@
 	data_req->trx_nr = trx;
 	data_req->ts_nr = ts;
 	data_req->block_nr = block_nr;
-	memcpy(data_req->data, data, len);
+	if (len)
+		memcpy(data_req->data, data, len);
 	data_req->len = len;
 
 	return pcu_sock_send(msg);
@@ -223,12 +224,20 @@
 {
 #ifdef ENABLE_DIRECT_PHY
 	if (bts->trx[trx].fl1h) {
+		if (!msg) /* Simply skip sending idle frames to L1 */
+			return;
 		l1if_pdch_req(bts->trx[trx].fl1h, ts, 0, fn, arfcn, block_nr,
 			msg->data, msg->len);
 		msgb_free(msg);
 		return;
 	}
 #endif
+	if (!msg) {
+		pcu_tx_data_req(bts, trx, ts, PCU_IF_SAPI_PDTCH, arfcn, fn, block_nr,
+				NULL, 0);
+		return;
+	}
+
 	pcu_tx_data_req(bts, trx, ts, PCU_IF_SAPI_PDTCH, arfcn, fn, block_nr,
 			msg->data, msg->len);
 	msgb_free(msg);
@@ -243,10 +252,17 @@
 		gsmtap_send(the_pcu->gsmtap, arfcn, ts, GSMTAP_CHANNEL_PTCCH, 0, fn, 0, 0, data, data_len);
 #ifdef ENABLE_DIRECT_PHY
 	if (bts->trx[trx].fl1h) {
+		if (!data_len) /* Simply skip sending idle frames to L1 */
+			return;
 		l1if_pdch_req(bts->trx[trx].fl1h, ts, 1, fn, arfcn, block_nr, data, data_len);
 		return;
 	}
 #endif
+	if (!data_len) {
+		pcu_tx_data_req(bts, trx, ts, PCU_IF_SAPI_PTCCH, arfcn, fn, block_nr, NULL, 0);
+		return;
+	}
+
 	pcu_tx_data_req(bts, trx, ts, PCU_IF_SAPI_PTCCH, arfcn, fn, block_nr, data, data_len);
 }
 
@@ -544,8 +560,11 @@
 		 * TRX0, since BTS is not preparing dummy bursts on idle TS for us: */
 		skip_idle = skip_idle && trx != 0;
 #endif
-	if (skip_idle)
+	if (skip_idle) {
+		pcu_l1if_tx_ptcch(bts, trx, ts, bts->trx[trx].arfcn, fn, block_nr,
+				  NULL, 0);
 		return 0;
+	}
 
 	pcu_l1if_tx_ptcch(bts, trx, ts, bts->trx[trx].arfcn, fn, block_nr,
 			  pdch->ptcch_msg, GSM_MACBLOCK_LEN);

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Gerrit-Project: osmo-pcu
Gerrit-Branch: master
Gerrit-Change-Id: Ife718eeed2af011479c03099ea109518f04567bc
Gerrit-Change-Number: 25535
Gerrit-PatchSet: 1
Gerrit-Owner: pespin <pespin at sysmocom.de>
Gerrit-MessageType: newchange
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