Serious problem: Crossfire receiver with Plane 4.6.0 beta1: no reconnection after failsafe

[dxs94]

Bug report

Issue details

Crossfire nano RX, Micro TX V2, TX16S, FW 6.36.
Matek 405 Wing board.
Plane was fine on 4.5.5 beta1, no failure. Flashed 4.6.0 beta1 (also tried latest as of 02 dec 2024), the RC link works as expected. However triggering failsafe by turning radio OFF then ON results in receiver reconnecting as expected (green LED on receiver plus basic telemetry recovered on radio side), however there is no link between flight controller and receiver: no command received from radio, no extended telemetry. Regaining control from radio is impossible and would result in a crash in real life. Rebooting the flight controller restores the link.

Version
4.6.0 beta1 and latest (02 dec 24)

Platform
[ ] All
[ ] AntennaTracker
[ ] Copter
[x] Plane
[ ] Rover
[ ] Submarine

Airframe type
Regular plane

Hardware type
Matek F405 Wing

Logs
None

[andyp1per]

I've reproduced this on tracer.

[rmackay9]

Great, thanks for the report, I've added this to the 4.6 issues list

[Yury-MonZon]

Recently I've had this unrecoverable FS on 4.5.7 (pixhawk1 with elrs) during the flight. I've had to wait for my battery to drain and then the plane landed in RTL. After battery reconnection - link was back and working fine. I wasn't sure what caused it.

Today after seeing this issue I managed to replicate this behavior on another plane (4.6.0beta1 SpeedyBeeF405wing with elrs) to the extent that I don't get link reconnected on first try. It goes up and down a few times and then stays connected.

Here is the rundown from MP(starts from the bottom):

12/4/2024 01:38:57 : RC Long Failsafe Cleared
12/4/2024 01:38:57 : Throttle failsafe off
12/4/2024 01:38:53 : RC Long Failsafe On: RTL
12/4/2024 01:38:48 : RC Short Failsafe On
12/4/2024 01:38:48 : Throttle failsafe on
12/4/2024 01:38:47 : RC Long Failsafe Cleared
12/4/2024 01:38:47 : Throttle failsafe off
12/4/2024 01:38:44 : RC Long Failsafe On: RTL
12/4/2024 01:38:39 : RC Short Failsafe On
12/4/2024 01:38:39 : Throttle failsafe on
12/4/2024 01:38:36 : RC Long Failsafe Cleared
12/4/2024 01:38:36 : Throttle failsafe off
RADIO ON
12/4/2024 01:38:16 : RC Long Failsafe On: RTL
12/4/2024 01:38:10 : RC Short Failsafe: switched to FLY_BY_WIRE_A
12/4/2024 01:38:10 : Throttle failsafe on
RADIO OFF
12/4/2024 01:37:35 : CRSFv2: requesting RX device info
12/4/2024 01:37:35 : CRSFv2: RSSI now displays  as LQ
12/4/2024 01:37:35 : CRSFv2: RSSI now displays  as LQ
12/4/2024 01:37:35 : RCInput: decoding CRSF(3)
RADIO ON

log2.zip

Once I had it going up and down without getting permanently connected even after a few minutes, but I didn't have logs enabled that time.

In both cases fw was compiled with those defines:

define HAL_CRSF_TELEM_TEXT_SELECTION_ENABLED OSD_ENABLED && OSD_PARAM_ENABLED && HAL_CRSF_TELEM_ENABLED
define AP_OSD_LINK_STATS_EXTENSIONS_ENABLED 1

[andyp1per]

This appears to be caused by #26880