tty: serial: lpuart: disable flow control while waiting for the transmit engine to...

When the user initializes the uart port, and waits for the transmit
engine to complete in lpuart32_set_termios(), if the UART TX fifo has
dirty data and the UARTMODIR enable the flow control, the TX fifo may
never be empty. So here we should disable the flow control first to make
sure the transmit engin can complete.

Fixes: 380c966c093e ("tty: serial: fsl_lpuart: add 32-bit register interface support")
Cc: stable <stable@kernel.org>
Signed-off-by: Sherry Sun <sherry.sun@nxp.com>
Link: https://lore.kernel.org/r/20220821101527.10066-1-sherry.sun@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index e9ba0f0..b20f6f2 100644 (file)
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -2191,6 +2191,7 @@ lpuart32_set_termios(struct uart_port *port, struct ktermios *termios,
        uart_update_timeout(port, termios->c_cflag, baud);
 
        /* wait transmit engin complete */
+       lpuart32_write(&sport->port, 0, UARTMODIR);
        lpuart32_wait_bit_set(&sport->port, UARTSTAT, UARTSTAT_TC);
 
        /* disable transmit and receive */