fn set_tx_fifo_empty_threshold(&self, threshold: u16) -> Result<(), ConfigError> {
        if threshold > Self::TX_FIFO_MAX_THRHD {
            return Err(ConfigError::UnsupportedTxFifoThreshold);
        }

        self.regs()
            .conf1()
            .modify(|_, w| unsafe { w.txfifo_empty_thrhd().bits(threshold as _) });

        Ok(())
    }
Configures the TX-FIFO threshold

## Errors

[ConfigError::UnsupportedTxFifoThreshold] if the provided value exceeds
[`Info::TX_FIFO_MAX_THRHD`].
esp-hal/src/uart.rs