part 1 of: fix SAPIs for handover to match 48.058 4.1.{3,4}

This part adds the common lchan flags to indicate whether DL SACCH
should be activated.

Note that currently, osmo-bsc *always* sends the MS Power IE as well as
the TA IE, also for inter-cell HO, so in the osmoverse, nothing will
change until we also adjust osmo-bsc. See OS#4858.

Change-Id: Ibea973ccadf5d424213f141f97a61395856b76de

1 files changed, 16 insertions, 0 deletions

diff --git a/include/osmo-bts/gsm_data.h b/include/osmo-bts/gsm_data.h
index 1c1c5d44..7670508a 100644
--- a/include/osmo-bts/gsm_data.h
+++ b/include/osmo-bts/gsm_data.h
@@ -194,6 +194,22 @@ struct gsm_lchan {
 
 	char *name;
 
+	/* For handover, activation is described in 3GPP TS 48.058 4.1.3 and 4.1.4:
+	 *
+	 *          |          | Access ||  transmit         |  activate
+	 *          | MS Power | Delay  ||  on main channel  |  dl SACCH
+	 * ----------------------------------------------------------------------
+	 * async ho   no         *     -->  yes                 no
+	 * async ho   yes        *     -->  yes                 may be started
+	 * sync ho    no         no    -->  yes                 no
+	 * sync ho    yes        no    -->  yes                 may be started
+	 * sync ho    yes        yes   -->  yes                 shall be started
+	 *
+	 * Always start the main channel immediately.
+	 * want_dl_sacch_active indicates whether dl SACCH should be activated on CHAN ACT.
+	 */
+	bool want_dl_sacch_active;
+
 	/* Number of different GsmL1_Sapi_t used in osmo_bts_sysmo is 23.
 	 * Currently we don't share these headers so this is a magic number. */
 	struct llist_head sapi_cmds;