From 016c8b616df0447ba151f7b24294fe16cf18fe79 Mon Sep 17 00:00:00 2001
From: Vadim Yanitskiy <vyanitskiy@sysmocom.de>
Date: Thu, 14 Apr 2022 01:19:43 +0300
Subject: [PATCH] osmo-bts-trx: amr_loop: trigger the loop unconditionally

The logic responsible for enabling and disabling the loop appears
to be broken: during my experiments trx_loop_amr_set() was never
called with loop=1.  It's not clear what's the motivation behind
this breaker, so I propose to rip it out for now.  This patch
finally makes the loop work (confirmed with a TEMS phone).

Related: SYS#5917, OS#4984
Change-Id: I09b649973d4269c4082a4fafa493c37825f95a9c
(cherry picked from commit 541b7525aee81fbeed23be9cddf909ebcca6ed6d)
---
 include/osmo-bts/scheduler.h        |  1 -
 src/osmo-bts-trx/amr_loop.c         | 17 -----------------
 src/osmo-bts-trx/sched_lchan_tchf.c | 13 +------------
 3 files changed, 1 insertion(+), 30 deletions(-)

diff --git a/include/osmo-bts/scheduler.h b/include/osmo-bts/scheduler.h
index ec31eab9b..c96b70b46 100644
--- a/include/osmo-bts/scheduler.h
+++ b/include/osmo-bts/scheduler.h
@@ -119,7 +119,6 @@ struct l1sched_chan_state {
 	uint8_t			dl_ft;		/* current downlink FT index */
 	uint8_t			ul_cmr;		/* current uplink CMR index */
 	uint8_t			dl_cmr;		/* current downlink CMR index */
-	uint8_t			amr_loop;	/* if AMR loop is enabled */
 	uint8_t			amr_last_dtx;	/* last received dtx frame type */
 
 	/* TCH/H */
diff --git a/src/osmo-bts-trx/amr_loop.c b/src/osmo-bts-trx/amr_loop.c
index ce89091ab..859f39bf7 100644
--- a/src/osmo-bts-trx/amr_loop.c
+++ b/src/osmo-bts-trx/amr_loop.c
@@ -40,10 +40,6 @@ void trx_loop_amr_input(struct l1sched_chan_state *chan_state,
 	const uint8_t mi = chan_state->ul_ft; /* mode index 0..3 */
 	int lqual_cb = meas_set->ci_cb; /* cB (centibel) */
 
-	/* check if loop is enabled */
-	if (!chan_state->amr_loop)
-		return;
-
 	/* count per-block C/I samples for further averaging */
 	if (lchan->type == GSM_LCHAN_TCH_H) {
 		chan_state->lqual_cb_num += 2;
@@ -109,16 +105,3 @@ void trx_loop_amr_input(struct l1sched_chan_state *chan_state,
 	LOGPLCHAN(lchan, DLOOP, LOGL_DEBUG, "Keeping the current AMR codec "
 		  "mode[%u]=%u\n", mi, cfg->mode[mi].mode);
 }
-
-void trx_loop_amr_set(struct l1sched_chan_state *chan_state, int loop)
-{
-	if (chan_state->amr_loop == loop)
-		return;
-	if (!chan_state->amr_loop) {
-		/* reset the link quality measurements */
-		chan_state->lqual_cb_num = 0;
-		chan_state->lqual_cb_sum = 0;
-	}
-
-	chan_state->amr_loop = loop;
-}
diff --git a/src/osmo-bts-trx/sched_lchan_tchf.c b/src/osmo-bts-trx/sched_lchan_tchf.c
index 6a90327bb..b530d25dd 100644
--- a/src/osmo-bts-trx/sched_lchan_tchf.c
+++ b/src/osmo-bts-trx/sched_lchan_tchf.c
@@ -384,7 +384,7 @@ struct msgb *tch_dl_dequeue(struct l1sched_ts *l1ts, struct trx_dl_burst_req *br
 	if (msg_tch) {
 		int len;
 		uint8_t cmr_codec;
-		int cmr, ft, i;
+		int ft, i;
 		enum osmo_amr_type ft_codec;
 		enum osmo_amr_quality bfi;
 		int8_t sti, cmi;
@@ -416,22 +416,11 @@ struct msgb *tch_dl_dequeue(struct l1sched_ts *l1ts, struct trx_dl_burst_req *br
 				LOGL1SB(DL1P, LOGL_ERROR, l1ts, br, "Cannot send invalid AMR payload\n");
 				goto free_bad_msg;
 			}
-			cmr = -1;
 			ft = -1;
 			for (i = 0; i < chan_state->codecs; i++) {
-				if (chan_state->codec[i] == cmr_codec)
-					cmr = i;
 				if (chan_state->codec[i] == ft_codec)
 					ft = i;
 			}
-			if (cmr >= 0) { /* new request */
-				chan_state->dl_cmr = cmr;
-				/* disable AMR loop */
-				trx_loop_amr_set(chan_state, 0);
-			} else {
-				/* enable AMR loop */
-				trx_loop_amr_set(chan_state, 1);
-			}
 			if (ft < 0) {
 				LOGL1SB(DL1P, LOGL_ERROR, l1ts, br,
 					"Codec (FT = %d) of RTP frame not in list\n", ft_codec);