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

commit d5a2e0834364377a5d5a2fff1890a0b3f0bafd1f upstream.

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 5c44dc7be62f3e8ea9dfa9af48479d9f1aad8d01..f3f582c3dc874d5884d960e904a0bd7bbe4af8e7 100644 (file)
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -1981,6 +1981,7 @@ 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 */