channel_release: First attempt to update the doc to new code.
diff --git a/openbsc/doc/channel_release.txt b/openbsc/doc/channel_release.txt
index a10e9d5..0f1b73c 100644
--- a/openbsc/doc/channel_release.txt
+++ b/openbsc/doc/channel_release.txt
@@ -31,46 +31,65 @@
== Implementation in OpenBSC ==
-THIS IS OUTDATED and will be updated...
+There are two possible reasons a gsm_subscriber_connection
+will be released. One is a network failure, the other is
+the completion of an operation/transaction.
-chan_alloc.c:lchan_auto_release()
- * checks if use count still > 0 (abort)
- * calls gsm48_send_rr_release()
- * which calls rsl_deact_sacch()
- * calls rsl_release_request()
- * which sends RLL Link Release request
-
+=== Failure ===
+The BSC API will call the gsm_04_08.c:gsm0408_clear_request callback
+and the MSC part will release all transactions, operations and such
+and the channels will be released as error case.
+
+=== Success ===
+Every time an 'operation' or 'transaction' is finished msc_release_connection
+will be called and it will determine if the gsm_subscriber_connection can
+be released.
+
+In case it can be released bsc_api.c:gsm0808_clear will be called
+which will release all lchan's associated with the connection. For the
+primary channel a SACH Deactivate will be send with the release
+reason NORMAL RELEASE.
+
+
+bsc_api.c:gsm0808_clear
+ * Release a channel used for handover
+ * Release the primary lchan with normal release, SACH deactivate
+
+chan_alloc.c:lchan_release(chan, sach_deactivate, reason)
+ * Start release procedure. It is working in steps with callbacks
+ coming from the abis_rsl.c code.
+ * Release all SAPI's > 0, wait for them to be released
+ * Send SACH Deactivate on SAPI=0
+ * Finally Release the channel
+
RX of RELease INDication:
- * call rsl_rf_chan_release() (send RF_CHAN_REL)
+ * Calls internal rsl_handle_release which might release the RF.
+ * Informs chan_alloc.c about the release with
+ rsl_lchan_rll_release.
RX of RELease CONFimem:
- * call rsl_rf_chan_release() (send RF_CHAN_REL)
+ * Calls internal rsl_handle_release which might release the RF.
+ * Informs chan_alloc.c about the release with
+ rsl_lchan_rll_release.
* RX of RF_CHAN_REL_ACK
* call lchan_free()
- * subscr_put()
- * delete release_timer
=== Integration with SMS ===
* RX of CP_ERROR or unimplemented MT
- * trigger trans_free() which will lchan_auto_release()
+ * trigger trans_free() which will msc_release_connection()
* CP TC1* expired while waiting for CP-ACK
- * trigger trans_free() which will lchan_auto_release()
+ * trigger trans_free() which will msc_release_connection()
* RX of RP_ERROR
- * trigger trans_free() which will lchan_auto_release()
+ * trigger trans_free() which will msc_release_connection()
* TX of CP-ACK in MT DELIVER
- * trigger trans_free() which will lchan_auto_release()
+ * trigger trans_free() which will msc_release_connection()
* RX of CP-ACK in MO SUBMIT
- * trigger trans_free() which will lchan_auto_release()
+ * trigger trans_free() which will msc_release_connection()
-* RX of RP-ACK in MT DELIVER (and no more messages)
- * trigger rsl_release_request() for SAPI3
-
-* RX of RP-SMMA in MT DELIVER (and no more messages)
- * trigger rsl_release_request() for SAPI3