dyn TS: clearly use lchan[0], fixing minor confusion

The dyn_ts_switchover_*() functions made the impression that they act on a
specific lchan of a timeslot. The assumption that we would remember to use e.g.
lchan[1] across a PDCH deactivation is brain damaged to begin with; and
factually we always use lchan[0] anyway (the only case for using lchan[1] would
be when switching to TCH/H, but the channel allocator will always return
lchan[0] for that).

Instead of the brain damaged lchan args, use a ts arg across all
dyn_ts_switchover_*() functions, with one exception: The
dyn_ts_switchover_complete() actually receives an RSL activation ack message on
a specific lchan and needs to evaluate its lchan type. This will always be
lchan[0] as it is now, but we should stick with the lchan the message was sent
for.

For PDCH, a check to use lchan[0] already existed, when composing the ACT
message in rsl_chan_activate_lchan_as_pdch(). Replace with an assertion.

Adjust all callers to pass ts instead of lchan.

In dyn_ts_switchover_start(), there was a dead code check that jumps to
switchover_complete() in case the pchan already matches. This never hits,
because we only call dyn_ts_switchover_start() when pchans mismatch. So avoid
guessing at passing lchan[0] to dyn_ts_switchover_complete() by not calling it
at all but logging an error instead.

In rsl_chan_activate_lchan(), we remember some values before going into
switchover from PDCH. Explicitly store them in lchan[0], because after a PDCH
release we have always and will activate no other than lchan[0].

In dyn_ts_switchover_continue(), move the check for any existing lchan->rqd_ref
further above, and more correctly check all lchans that were so far valid on
the TS, instead of just one.

This partly prepares for a subsequent commit to fix the act_timer use for dyn
TS: with the old lchan arg, we might schedule an activation timer on lchan[1]
but receive an ack on lchan[0] (for PDCH), leading to an act_timer expiry.

Change-Id: I3f5d48a9bdaa49a42a1908d4a03744638c59796a

1 files changed, 1 insertions, 1 deletions

diff --git a/openbsc/include/openbsc/abis_rsl.h b/openbsc/include/openbsc/abis_rsl.h
index 8313f489e..758c5557a 100644
--- a/openbsc/include/openbsc/abis_rsl.h
+++ b/openbsc/include/openbsc/abis_rsl.h
@@ -108,7 +108,7 @@ int rsl_start_t3109(struct gsm_lchan *lchan);
 int rsl_direct_rf_release(struct gsm_lchan *lchan);
 
 void dyn_ts_init(struct gsm_bts_trx_ts *ts);
-int dyn_ts_switchover_start(struct gsm_lchan *lchan,
+int dyn_ts_switchover_start(struct gsm_bts_trx_ts *ts,
 			    enum gsm_phys_chan_config to_pchan);
 
 #endif /* RSL_MT_H */