[PATCH] openbsc[master]: dyn TS: OS#1778 workaround: disable TCH/F on dyn TS for nitb

[Neels Hofmeyr]

Hello Harald Welte, Jenkins Builder,

I'd like you to reexamine a change.  Please visit

    https://gerrit.osmocom.org/603

to look at the new patch set (#3).

dyn TS: OS#1778 workaround: disable TCH/F on dyn TS for nitb

To avoid two phones picking mismatching TCH pchans, never pick TCH/F on dynamic
TS for now, when compiled as osmo-nitb.

See http://osmocom.org/issues/1778

Related: OS#1778
Change-Id: If7e4797a72815fc6e2bbef27756ea5df69f4bde7
---
M openbsc/src/libbsc/chan_alloc.c
1 file changed, 13 insertions(+), 0 deletions(-)


  git pull ssh://gerrit.osmocom.org:29418/openbsc refs/changes/03/603/3

diff --git a/openbsc/src/libbsc/chan_alloc.c b/openbsc/src/libbsc/chan_alloc.c
index 1e5dd74..fa89a76 100644
--- a/openbsc/src/libbsc/chan_alloc.c
+++ b/openbsc/src/libbsc/chan_alloc.c
@@ -309,6 +309,18 @@
 			if (lchan)
 				type = GSM_LCHAN_TCH_F;
 		}
+#ifdef ROLE_BSC
+		/*
+		 * For osmo-nitb, skip TCH/F for now, because otherwise dyn TS
+		 * always imply the possibility to have a mix of TCH/F and
+		 * TCH/H channels; if two phones request a TCH/F and a TCH/H,
+		 * respectively, they cannot call each other. If we deny TCH/F,
+		 * they will both fall back to TCH/H, and dynamic channels are
+		 * usable. See http://osmocom.org/issues/1778.
+		 *
+		 * A third-party MSC may well be able to handle a TCH/H TCH/F
+		 * mismatch.
+		 */
 		/* Try fully dynamic TCH/F_TCH/H_PDCH as TCH/F... */
 		if (!lchan) {
 			lchan = _lc_dyn_find_bts(bts,
@@ -317,6 +329,7 @@
 			if (lchan)
 				type = GSM_LCHAN_TCH_F;
 		}
+#endif
 		/* ...and as TCH/H. */
 		if (!lchan) {
 			lchan = _lc_dyn_find_bts(bts,

-- 
To view, visit https://gerrit.osmocom.org/603
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Gerrit-MessageType: newpatchset
Gerrit-Change-Id: If7e4797a72815fc6e2bbef27756ea5df69f4bde7
Gerrit-PatchSet: 3
Gerrit-Project: openbsc
Gerrit-Branch: master
Gerrit-Owner: Neels Hofmeyr <nhofmeyr at sysmocom.de>
Gerrit-Reviewer: Harald Welte <laforge at gnumonks.org>
Gerrit-Reviewer: Jenkins Builder
Gerrit-Reviewer: neels_test_account <neels at hofmeyr.de>