Adding a FIXME regarding changing serialrx_provider at runtime.

src/main/rx/rx.c

@@ -172,7 +172,15 @@ void serialRxInit(rxConfig_t *rxConfig)
 
 bool isSerialRxFrameComplete(rxConfig_t *rxConfig)
 {
-
+    /**
+     * FIXME: Each of the xxxxFrameComplete() methods MUST be able to survive being called without the
+     * corresponding xxxInit() method having been called first.
+     *
+     * This situation arises when the cli or the msp changes the value of rxConfig->serialrx_provider
+     *
+     * A solution is for the ___Init() to configure the serialRxFrameComplete function pointer which
+     * should be used instead of the switch statement below.
+     */
     switch (rxConfig->serialrx_provider) {
         case SERIALRX_SPEKTRUM1024:
         case SERIALRX_SPEKTRUM2048: