* If RSSI Channel is set to Disabled when using S.Bus then generate RSSI signal using frame drop flags from the rx
* Set RSSI max level for S.Bus to 1024 so OSD defaults can be used
* Failsfafe must be detected rather than just reporting dropped frames
* Failsafe implies dropped frames
* Remove failsafe debug
* Use RSSI_SOURCE_RX_PROTOCOL
* Add rssi_from_rx_protocol to enable siqnal quality from rx to be processed as RSSI
* Use RSSI_MAX_VALUE definition
* Use rssi_from_rx_protocol flag for fport rx
* Update serialpassthrough help text
* Revert erroneous commit
* Use rssi_src_frame_errors boolean
* rssi_src_frame_errors = ON | OFF
* Moved rssi_src_frame_errors to end of rxConfig_t struct
* Add documentation of rssi_src_frame_errors
* Synthesise RX_FRAME_FAILSAFE flag to protect from bad implementation in receivers
* Match rx failsafe behaviour exactly
* Only set RX_FRAME_COMPLETE if valid frame is received
* RSSI_SOURCE_FRAME_ERRORS moved to end of rssiSource_e enum
* Removed superfluous else if clause
* Restore debug code
* Restore stateFlags
* Set RX_FRAME_DROPPED flag when failsafe is triggered
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