Radio: PANIC NULL transition (PREAMBLE while RX FIFO full)

[cire831]

We panic with a null transition. looks like a PREAMBLE_DETECT event occurred while we are still processing an older packet (in the fifo).

We need to review the interrupt processing order.

example:

  fsm_transition_t *fsm_select_transition(fsm_event_t ev, fsm_state_t st) {
    fsm_transition_t *ev_list;
    fsm_transition_t *trans;
    fsm_event_t n_events;

    n_events = NELEMS(fsm_events_group);
    if (ev >= n_events)
      __PANIC_RADIO(80, ev, st, 0, 0);

    trans = NULL;
    for (ev_list = (fsm_transition_t *) fsm_events_group[ev];
         ev_list && (ev_list->action != A_BREAK); ev_list++) {
      if ((ev_list->current_state == st) || (ev_list->current_state == S_DEFAULT)) {
        trans = ev_list;
        break;
      }
    }
    if (trans == NULL)
      __PANIC_RADIO(81, ev, st, 0, 0);
    return trans;
  }

we panic with the event E_PREAMBLE_DETECT.

And the fsm trace is:

t   109: time:0xc4557572(0x74  )  E_PREAMBLE_DETECT  S_RX_ON                    A_RX_START  S_RX_ACTIVE       
t   110: time:0xc4566849(0x12  )      E_SYNC_DETECT  S_RX_ACTIVE                     A_NOP  S_RX_ACTIVE       
t   111: time:0xc456b953(0x4ef )        E_RX_THRESH  S_RX_ACTIVE             A_RX_FETCH_FF  S_RX_ACTIVE       
t   112: time:0xc45713fe(0x4e2 )        E_RX_THRESH  S_RX_ACTIVE             A_RX_FETCH_FF  S_RX_ACTIVE       
t   113: time:0xc4576ed4(0x4e2 )        E_RX_THRESH  S_RX_ACTIVE             A_RX_FETCH_FF  S_RX_ACTIVE       

and spi traffic:

18  0xc4576dac  blen:slen 8:8, int_status_rsp_s  0101 0123 0089 0014    ph_pend:  RX_FIFO_ALMOST_FULL ph_status:  PACKET_SENT TX_FIFO_ALMOST_EMPTY RX_FIFO_ALMOST_FULL modem_status:  RSSI SYNC_DETECT chip_status:  STATE_CHANGE CHIP_READY
19  0xc4576e28  fast_frr_s  0800 0050   state: RX, rssi: 80
20  0xc4576e76  fast_frr_s  08   
21  0xc4576eb4  fast_frr_s  50   
22  0xc4576f80  1500   PARSE ERROR: fifo_info_rsp_s  1500 
23  0xc457701d  blen:slen 2:2, fifo_info_rsp_s  1c40   Container({'rx_fifo_count': 28, 'tx_fifo_space': 64, 'cts': 255})
24  0xc4577096  fast_frr_s  0800 1050   state: RX modem_pend:  RSSI_JUMP, rssi: 80
25  0xc4577143  fast_frr_s  0800 1050   state: RX modem_pend:  RSSI_JUMP, rssi: 80
26  0xc457739a  || SPI_REC_RX_FIFO  00  0x1c  cfff fce3 c7f7 efdd 5bfb bcdb b5fd 9fff   
27  0xc457742e  fast_frr_s  0900 1450   state: 0 modem_pend:  RSSI_JUMP INVALID_PREAMBLE, rssi: 80
28  0xc4577546  0x20 20 
29  0xc457764e  blen:slen 8:8, int_status_rsp_s  0002 0022 1489 0014    modem_pend:  RSSI_JUMP INVALID_PREAMBLE ph_status:  PACKET_SENT TX_FIFO_ALMOST_EMPTY modem_status:  RSSI SYNC_DETECT chip_status:  STATE_CHANGE CHIP_READY
30  0xc45776ca  fast_frr_s  0900 0050   state: 0, rssi: 80
31  0xc4577748  fast_frr_s  0900 0050   state: 0, rssi: 80
32  0xc4577862  0x20 20 
33  0xc457796a  blen:slen 8:8, int_status_rsp_s  0000 0022 0089 0014    ph_status:  PACKET_SENT TX_FIFO_ALMOST_EMPTY modem_status:  RSSI SYNC_DETECT chip_status:  STATE_CHANGE CHIP_READY
34  0xc45779e6  fast_frr_s  0900 0050   state: 0, rssi: 80
35  0xc457f357  fast_frr_s  0800 1650   state: RX modem_pend:  RSSI_JUMP INVALID_PREAMBLE PREAMBLE_DETECT, rssi: 80
36  0xc457f3d8  fast_frr_s  0800 1650   state: RX modem_pend:  RSSI_JUMP INVALID_PREAMBLE PREAMBLE_DETECT, rssi: 80
37  0xc457f4f0  0x20 20 
38  0xc457f5f8  blen:slen 8:8, int_status_rsp_s  0206 0022 168b 1014    modem_pend:  RSSI_JUMP INVALID_PREAMBLE PREAMBLE_DETECT chip_pend:  STATE_CHANGE ph_status:  PACKET_SENT TX_FIFO_ALMOST_EMPTY modem_status:  RSSI PREAMBLE_DETECT SYNC_DETECT chip_status:  STATE_CHANGE CHIP_READY
39  0xc457f674  fast_frr_s  0800 0050   state: RX, rssi: 80
40  0xc457f6c2  fast_frr_s  08   
41  0xc457f700  fast_frr_s  50