From d208bfef94ab83280de30ba4a0675ff73b3ecef3 Mon Sep 17 00:00:00 2001
From: = <=>
Date: Sun, 27 Sep 2026 20:39:33 +1300
Subject: [PATCH] Basic patch for LR2021 packet corruption from race +
 isReceiving tweaks for continuous mode

NOTE:
After trying a bunch of variants, these events are < 0.1% so I don't think it's worth the complexity to try read these, and the better approach is just reject all that risk having issues.
---
 src/helpers/radiolib/CustomLR2021.h       | 19 +++++++++++--------
 src/helpers/radiolib/RadioLibWrappers.cpp |  3 ++-
 2 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/src/helpers/radiolib/CustomLR2021.h b/src/helpers/radiolib/CustomLR2021.h
index a89ae94330..1dc2ba8d37 100644
--- a/src/helpers/radiolib/CustomLR2021.h
+++ b/src/helpers/radiolib/CustomLR2021.h
@@ -79,18 +79,10 @@ class CustomLR2021 : public LR2021 {
       uint32_t irq = getIrqStatus();
       bool preamble = irq & RADIOLIB_LR2021_IRQ_PREAMBLE_DETECTED;  // bit 5
       bool header   = irq & RADIOLIB_LR2021_IRQ_LORA_HEADER_VALID;  // bit 6
-      bool hdrErr   = irq & RADIOLIB_LR2021_IRQ_LORA_HDR_CRC_ERROR; // bit 9
       uint32_t now  = millis();
-      if (hdrErr) {
-        clearIrqFlags(RADIOLIB_LR2021_IRQ_PREAMBLE_DETECTED | RADIOLIB_LR2021_IRQ_LORA_HEADER_VALID | RADIOLIB_LR2021_IRQ_LORA_HDR_CRC_ERROR);
-        _activityAt = 0;
-        _headerSeen = false;
-        return false;
-      }
       if (!header && _headerSeen) {
         // something cleared the header flag, reset our state.
         _activityAt = 0; _headerSeen = false;
-        return false;
       }
 
       if (header) {
@@ -116,6 +108,17 @@ class CustomLR2021 : public LR2021 {
       _activityAt = 0; _headerSeen = false;
       return false;
     }
+
+    int16_t readData(uint8_t* data, size_t len) override {
+      uint16_t fifoLevel = 0;
+      getRxFifoLevel(&fifoLevel);
+      // If there's too few bytes it could be a ghost RX_DONE (0 bytes in buffer), late read with another whole packet in the buffer,
+      // late and we're mid writing the next packet to the fifo, or leftover data from last event clearing the buffer halfway through.
+      int16_t state = LR2021::readData(data, len);
+      RADIOLIB_ASSERT(state);
+      if (fifoLevel != len) { return RADIOLIB_ERR_PACKET_TOO_SHORT; }
+      return state;
+    }
     
     void setPreambleMillis(uint32_t preambleMillis) {
       _preambleMillis = preambleMillis;
diff --git a/src/helpers/radiolib/RadioLibWrappers.cpp b/src/helpers/radiolib/RadioLibWrappers.cpp
index b9c095ac40..845ec0d252 100644
--- a/src/helpers/radiolib/RadioLibWrappers.cpp
+++ b/src/helpers/radiolib/RadioLibWrappers.cpp
@@ -139,7 +139,8 @@ int RadioLibWrapper::recvRaw(uint8_t* bytes, int sz) {
       }
     }
     #if defined(USE_LR2021)
-    state = STATE_RX;     // LR2021 stays in Rx after readData, calling startReceive while still in Rx throws -706 errors
+    state = STATE_RX;     // LR2021 stays in Rx after readData, calling startReceive when not in standby throws -706 errors
+    _radio->clearIrqFlags(RADIOLIB_LR2021_IRQ_RX_DONE); // Ensure we never get stuck
     #else
     state = STATE_IDLE;   // need another startReceive()
     #endif