Ben Meadors 8ef996f5b4 fix(radio): never read a RadioLib error code as a packet's time on air (#11940) ...

* fix(radio): never read a RadioLib error code as a packet's time on air

getTimeOnAir() reads the packet type back over SPI on every chip and answers RADIOLIB_ERR_WRONG_MODEM when the chip is no longer in the mode we left it in (a reset or brownout leaves it in FSK). RadioLib returns times as an unsigned microsecond count and its negative int16_t error codes through that same value, so computePacketTime() divided -20 by 1000 and handed 4294967ms up as the time one packet spent on the air.

That single sample is enough to take the node off the air until it is rebooted:

  - channelUtilizationPercent() reads 7158% and utilizationTXPercent() 119%,
    matching the 7000%+ ChUtil spike and the 120% AirUtil in #11935, so both TX
    gates stay shut for the hour it takes that bucket to age out;
  - receiveDetected() uses the same figure as its false-header timeout, so
    activeReceiveStart is never cleared and canSendImmediately() sees a busy
    channel for 72 minutes.

Classify the returned value instead of trusting it. A failed getTimeOnAir() now falls back to calculateTimeOnAir() on the modem parameters we configured - arithmetic with no readback that can fail - and the RX path, which already used calculateTimeOnAir(), is guarded the same way.

Fixes #11935

* style: trunk fmt RadioLibInterface.h

2026-09-23 10:43:34 +00:00

..

test_main.cpp

fix(radio): never read a RadioLib error code as a packet's time on air (#11940)

2026-09-23 10:43:34 +00:00