50  *  2) Should we create pool of control pdu's?. Dont need more
52  *  if we have lots of connections.
58  *  5) We are supposed to remember when we do the data length update proc if
59  *  the device sent us an unknown rsp. We should not send it another len req.
61  *  8) How to count control pdus sent. DO we count enqueued + sent, or only
62  *  sent (actually attempted to tx). Do we count failures? How?
218  * NOTE: we dont have to reset the callout since this packet will have had a
231  * Called when we receive either a connection parameter request or response.
279      * or latency. If not, this may just be an anchor point change and we do  in ble_ll_ctrl_conn_param_pdu_proc()
281      *  XXX: what if we dont like the parameters? When do we check that out?  in ble_ll_ctrl_conn_param_pdu_proc()
296      * the host? Note that for a master we will not be processing a  in ble_ll_ctrl_conn_param_pdu_proc()
297      * connect param request from a slave if we are currently trying to  in ble_ll_ctrl_conn_param_pdu_proc()
299      * check is all we need for a master (when receiving a request).  in ble_ll_ctrl_conn_param_pdu_proc()
306          * has provided? Not sure what to do here. Do we need to remember what  in ble_ll_ctrl_conn_param_pdu_proc()
307          * host sent us? For now, I will assume that we need to remember what  in ble_ll_ctrl_conn_param_pdu_proc()
325      * XXX: are the connection update parameters acceptable? If not, we will  in ble_ll_ctrl_conn_param_pdu_proc()
326      * need to know before we indicate to the host that they are acceptable.  in ble_ll_ctrl_conn_param_pdu_proc()
329         /* If Host masked out Remote Connection Parameter Request Event, we need to  in ble_ll_ctrl_conn_param_pdu_proc()
338          * Send event to host. At this point we leave and wait to get  in ble_ll_ctrl_conn_param_pdu_proc()
380      * Set instant. We set the instant to the current event counter plus  in ble_ll_ctrl_conn_upd_make()
382      * at every connection interval and we are not sure when the connect  in ble_ll_ctrl_conn_upd_make()
383      * request will actually get sent. We add one more event plus the  in ble_ll_ctrl_conn_upd_make()
389      * XXX: This should change in the future, but for now we will just  in ble_ll_ctrl_conn_upd_make()
396         /* XXX: so we need to make the new anchor point some time away  in ble_ll_ctrl_conn_upd_make()
398            that here. We dont need to, but we should. */  in ble_ll_ctrl_conn_upd_make()
440     /* Set flag in state machine to denote we have scheduled an update */  in ble_ll_ctrl_conn_upd_make()
502     /* If we are running this one currently, stop it */  in ble_ll_ctrl_proc_unk_rsp()
522  * this is called, it means that we need to end the connection because it
575     /* Must check if we need to start host procedure */  in ble_ll_ctrl_phy_update_proc_complete()
644  *  There are no BER metrics and RSSI does not give you S/N so for now we will
717      * If not changing we still send update ind. Check if hosts expects  in ble_ll_ctrl_phy_update_ind_make()
734         /* Determine instant we will use. 6 more is minimum */  in ble_ll_ctrl_phy_update_ind_make()
767     /* If no preference we use current phy */  in ble_ll_ctrl_phy_req_rsp_make()
788      * XXX: TODO if we have an instant in progress we should end connection.  in ble_ll_ctrl_rx_phy_req()
793     /* Check if we have already initiated a procedure with an instant */  in ble_ll_ctrl_rx_phy_req()
811         /* XXX: deal with other control procedures that we need to stop */  in ble_ll_ctrl_rx_phy_req()
825         /* XXX: TODO: if we started another procedure with an instant  in ble_ll_ctrl_rx_phy_req()
826          * why are we doing this? Need to look into this.*/  in ble_ll_ctrl_rx_phy_req()
920      * XXX: Should we check to see if we are expecting to receive one  in ble_ll_ctrl_rx_phy_update_ind()
921      * of these, and if not, kill connection? Meaning we better be  in ble_ll_ctrl_rx_phy_update_ind()
924     /* get the new phy masks and see if we need to change */  in ble_ll_ctrl_rx_phy_update_ind()
954         /* If instant is in the past, we have to end the connection */  in ble_ll_ctrl_rx_phy_update_ind()
1031  * Called to determine if this is a control PDU we are allowed to send. This
1037  * dont try to check for them but we could do more... for example there are
1232     /* Calculate session key now that we have received the ENC_RSP */  in ble_ll_ctrl_rx_enc_rsp()
1234         /* In case we were already encrypted we need to reset packet counters */  in ble_ll_ctrl_rx_enc_rsp()
1247  * Called when we have received a LL control encryption request PDU. This
1260  * NOTE: if this is received by a master we will silently discard the PDU
1275     /* In case we were already encrypted we need to reset packet counters */  in ble_ll_ctrl_rx_enc_req()
1315         /* We only want to send a START_ENC_RSP if we havent yet */  in ble_ll_ctrl_rx_start_enc_req()
1332      * The spec does not say what to do here, but if we receive a pause  in ble_ll_ctrl_rx_pause_enc_req()
1333      * encryption request and we are not encrypted, what do we do? We  in ble_ll_ctrl_rx_pause_enc_req()
1370  * Called when we have received a LL_CTRL_START_ENC_RSP.
1390     /* If master, we are done. Stop control procedure and sent event to host */  in ble_ll_ctrl_rx_start_enc_rsp()
1392         /* We are encrypted */  in ble_ll_ctrl_rx_start_enc_rsp()
1406      * to send it before we transmit our own START_ENC_RSP.  in ble_ll_ctrl_rx_start_enc_rsp()
1429     /* If we were passed in a request, we use the parameters from the request */  in ble_ll_ctrl_conn_param_pdu_make()
1469     /* Set flag to denote we have sent/received this */  in ble_ll_ctrl_version_ind_make()
1529  * Called when we have received a LL_REJECT_IND or LL_REJECT_IND_EXT link
1551        if we receive ind ext? */  in ble_ll_ctrl_rx_reject_ind()
1555             /* As a master we should send connection update indication in this point */  in ble_ll_ctrl_rx_reject_ind()
1581          * However we need this workaround as there are devices on the market  in ble_ll_ctrl_rx_reject_ind()
1594  * Called when we receive a connection update event
1622     /* XXX: validate them at some point. If they dont check out, we  in ble_ll_ctrl_rx_conn_update()
1626     /* If instant is in the past, we have to end the connection */  in ble_ll_ctrl_rx_conn_update()
1637          * first packet received in connection event. Given that we increment  in ble_ll_ctrl_rx_conn_update()
1639          * the event counter what we do here is increment the instant and set  in ble_ll_ctrl_rx_conn_update()
1674  * Called when we receive a feature request or a slave initiated feature
1693      * Only accept slave feature requests if we are a master and feature  in ble_ll_ctrl_rx_feature_req()
1694      * requests if we are a slave.  in ble_ll_ctrl_rx_feature_req()
1713      * controller - we call this 'connection features'  in ble_ll_ctrl_rx_feature_req()
1725     /* If this is the first time we received remote features, try to start DLE */  in ble_ll_ctrl_rx_feature_req()
1753      * implementation. If we get a connection parameter request and we  in ble_ll_ctrl_rx_conn_param_req()
1757      * means that we will simply discard the connection parameter request  in ble_ll_ctrl_rx_conn_param_req()
1764      * initiated a procedure we may have received its connection parameter  in ble_ll_ctrl_rx_conn_param_req()
1766      * is the case, we will need to drop the host command when we get it  in ble_ll_ctrl_rx_conn_param_req()
1773      * Check for procedure collision (Vol 6 PartB 5.3). If we are a slave  in ble_ll_ctrl_rx_conn_param_req()
1774      * and we receive a request we "consider the slave initiated  in ble_ll_ctrl_rx_conn_param_req()
1778      * If a master, we send reject with a  in ble_ll_ctrl_rx_conn_param_req()
1795      * If we are a master and we currently performing a channel map  in ble_ll_ctrl_rx_conn_param_req()
1796      * update procedure we need to return an error  in ble_ll_ctrl_rx_conn_param_req()
1825      * procedure and the master initiated one as well. If we do get in this  in ble_ll_ctrl_rx_conn_param_rsp()
1827      * procedure when we reply.  in ble_ll_ctrl_rx_conn_param_rsp()
1833     /* If we receive a response and no procedure is pending, just leave */  in ble_ll_ctrl_rx_conn_param_rsp()
1899     /* If instant is in the past, we have to end the connection */  in ble_ll_ctrl_rx_chanmap_req()
1982             /* If we are already encrypted we do pause procedure */  in ble_ll_ctrl_proc_init()
2085  * Called to start a LL control procedure except for the terminate procedure. We
2120  * Called to determine if we need to start a LL control procedure for the given
2133      * ones are peer initiated. We need to wait. Deal with this.  in ble_ll_ctrl_chk_proc_start()
2137      * If we are terminating, dont start any new procedures but start  in ble_ll_ctrl_chk_proc_start()
2143              * If the terminate procedure has not started it means we were not  in ble_ll_ctrl_chk_proc_start()
2162                  * The version exchange is a special case. If we have already  in ble_ll_ctrl_chk_proc_start()
2207     /* XXX: where do we validate length received and packet header length?  in ble_ll_ctrl_rx_pdu()
2209      * is we should validate the over the air length with the mbuf length.  in ble_ll_ctrl_rx_pdu()
2235      * which would be an error, we will fail the check against the length  in ble_ll_ctrl_rx_pdu()
2247      * we shall respond with LL_UNKNOWN_RSP  in ble_ll_ctrl_rx_pdu()
2326          * If we have not started this procedure ourselves and it is  in ble_ll_ctrl_rx_pdu()
2339         /* According to specification, process this only if we asked for it. */  in ble_ll_ctrl_rx_pdu()
2342              * Process the received data. If received data is invalid, we'll  in ble_ll_ctrl_rx_pdu()
2343              * reply with LL_UNKNOWN_RSP as per spec, but we still need to stop  in ble_ll_ctrl_rx_pdu()
2361     /* XXX: check to see if ctrl procedure was running? Do we care? */  in ble_ll_ctrl_rx_pdu()
2365         /* If this is the first time we received remote features, try to start DLE */  in ble_ll_ctrl_rx_pdu()
2460             /* XXX: what happens if this fails? Meaning we cant allocate  in ble_ll_ctrl_rx_pdu()
2517  * This is called when we have a received a PDU during the ISR.
2541              * reason is LMP collision that means we are master on the link and  in ble_ll_ctrl_tx_done()
2542              * peer wanted to start procedure which we already started.  in ble_ll_ctrl_tx_done()