[PATCH] osmo-bts[master]: dyn TS: clear TCH state upon reconnecting as PDCH

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Neels Hofmeyr gerrit-no-reply at lists.osmocom.org
Sat May 5 18:37:19 UTC 2018


Review at  https://gerrit.osmocom.org/8038

dyn TS: clear TCH state upon reconnecting as PDCH

For ip.access style TCH/F_PDCH, this fixes switch-back to PDCH in case the TCH
use employed encryption.

For Osmocom style TCH/F_TCH/H_PDCH, do the same, purely out of sanity. Roughly
the same should already be happening during PDCH Chan Activ, but make sure to
clear all these fields, so they are cleared even if IEs are missing.

>From both dyn TS code paths, call new clear_lchan_for_pdch_activ(), which
clears the same fields that are normally overwritten by an RSL Chan Activ.

Related: OS#3238
Change-Id: I8451039683b54bee910c97c5a3e6873e0ff1b160
---
M src/common/rsl.c
1 file changed, 26 insertions(+), 0 deletions(-)


  git pull ssh://gerrit.osmocom.org:29418/osmo-bts refs/changes/38/8038/1

diff --git a/src/common/rsl.c b/src/common/rsl.c
index 1dc200d..52eb5f4 100644
--- a/src/common/rsl.c
+++ b/src/common/rsl.c
@@ -871,6 +871,26 @@
 	return 0;
 }
 
+/* Make sure no state from TCH use remains. */
+static void clear_lchan_for_pdch_activ(struct gsm_lchan *lchan)
+{
+	/* These values don't apply to PDCH, just clear them. Particularly the encryption must be
+	 * cleared, or we would enable encryption on PDCH with parameters remaining from the TCH. */
+	lchan->ms_power = ms_pwr_ctl_lvl(lchan->ts->trx->bts->band, 0);
+	lchan->ms_power_ctrl.current = lchan->ms_power;
+	lchan->ms_power_ctrl.fixed = 0;
+	lchan->rsl_cmode = 0;
+	lchan->tch_mode = 0;
+	memset(&lchan->encr, 0, sizeof(lchan->encr));
+	memset(&lchan->ho, 0, sizeof(lchan->ho));
+	lchan->bs_power = 0;
+	lchan->ms_power = 0;
+	memset(&lchan->ms_power_ctrl, 0, sizeof(lchan->ms_power_ctrl));
+	lchan->rqd_ta = 0;
+	copy_sacch_si_to_lchan(lchan);
+	memset(&lchan->tch, 0, sizeof(lchan->tch));
+}
+
 /*!
  * Store the CHAN_ACTIV msg, connect the L1 timeslot in the proper type and
  * then invoke rsl_rx_chan_activ() with msg.
@@ -882,7 +902,10 @@
 	switch (ts->dyn.pchan_want) {
 	case GSM_PCHAN_TCH_F:
 	case GSM_PCHAN_TCH_H:
+		break;
 	case GSM_PCHAN_PDCH:
+		/* Only the first lchan matters for PDCH */
+		clear_lchan_for_pdch_activ(ts->lchan);
 		break;
 	default:
 		LOGP(DRSL, LOGL_ERROR,
@@ -2096,6 +2119,9 @@
 	}
 
 	if (pdch_act) {
+		/* Clear TCH state. Only first lchan matters for PDCH */
+		clear_lchan_for_pdch_activ(ts->lchan);
+
 		/* First, disconnect the TCH channel, to connect PDTCH later */
 		rc = bts_model_ts_disconnect(ts);
 	} else {

-- 
To view, visit https://gerrit.osmocom.org/8038
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Gerrit-MessageType: newchange
Gerrit-Change-Id: I8451039683b54bee910c97c5a3e6873e0ff1b160
Gerrit-PatchSet: 1
Gerrit-Project: osmo-bts
Gerrit-Branch: master
Gerrit-Owner: Neels Hofmeyr <nhofmeyr at sysmocom.de>



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