The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From d5a2e0834364377a5d5a2fff1890a0b3f0bafd1f Mon Sep 17 00:00:00 2001 From: Sherry Sun sherry.sun@nxp.com Date: Sun, 21 Aug 2022 18:15:27 +0800 Subject: [PATCH] tty: serial: lpuart: disable flow control while waiting for the transmit engine to complete

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 e9ba0f0bd441..b20f6f2fa51c 100644 --- 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 */