This peripheral has dedicated control bits that flip input/output signals before handing them off to the OS. This is useful on my hardware because the UART is connected to an RS-422 transceiver with the +/- pins hooked up backward. Instead of a hack flipping all the bits before sending them, the hardware can do it for free. v4 cleans up the bit manipulation in v3; see previous series at https://lore.kernel.org/linux-serial/20200212163538.3006-1-ghilliard@xxxxxxxxxxxxxxx/ George Hilliard (2): dt-bindings: serial: document fsl,inverted-tx and -rx options tty: imx serial: Implement support for reversing TX and RX polarity .../bindings/serial/fsl-imx-uart.txt | 4 ++ drivers/tty/serial/imx.c | 44 ++++++++++++------- 2 files changed, 32 insertions(+), 16 deletions(-) -- 2.25.0
