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Fix Betaflight Passthrough broken by line-coding mirror (9.1 regression) #11834

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Fix Betaflight Passthrough broken by line-coding mirror (9.1 regression) #11834

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1033b5a
Fix Betaflight Passthrough broken by line-coding mirror
sensei-hacker Aug 28, 2026
3803359
Capture VCP mirror baseline before passthrough drain waits
sensei-hacker Aug 28, 2026
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13 changes: 10 additions & 3 deletions src/main/io/serial.c
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Original file line number Diff line number Diff line change
Expand Up @@ -615,9 +615,16 @@ void serialPassthrough(serialPort_t *left, serialPort_t *right, serialConsumer
LED1_OFF;

#ifdef USE_VCP
// Track current encoding applied to right port for VCP mirroring
portOptions_t currentOptions = right->options;
uint32_t currentBaudRate = right->baudRate;
// Track current encoding applied to right port for VCP mirroring.
// Baseline from the HOST's line coding at passthrough entry, not from the
// right port's settings: the mirror must only react to host-side CHANGES
// during the session. Initializing from right->baudRate/options would make
// the first mirror tick rewrite the passthrough UART's explicitly-requested
// encoding (e.g. CLI `serialpassthrough <id> 420000`) with whatever the
// host COM port is currently set to (115200 during the CLI session),
// breaking ELRS/Betaflight passthrough flashing (issue #11783).
portOptions_t currentOptions = usbVcpGetLineCoding();
uint32_t currentBaudRate = usbVcpGetBaudRate(left);
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bool leftIsVcp = (left->identifier == SERIAL_PORT_USB_VCP);
uint32_t lastMirrorTime = 0;
#endif
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