6.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: Sherry Sun sherry.sun@nxp.com
[ Upstream commit e98ab45ec5182605d2e00114cba3bbf46b0ea27f ]
No need to overwrite the whole UARTMODIR register before waiting the transmit engine complete, actually our target here is only to disable CTS flow control to avoid the dirty data in TX FIFO may block the transmit engine complete. Also delete the following duplicate CTS disable configuration.
Fixes: d5a2e0834364 ("tty: serial: lpuart: disable flow control while waiting for the transmit engine to complete") Cc: stable stable@kernel.org Signed-off-by: Sherry Sun sherry.sun@nxp.com Link: https://lore.kernel.org/r/20250307065446.1122482-1-sherry.sun@nxp.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/tty/serial/fsl_lpuart.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c index c2b522843b72c..951c3cdac3b94 100644 --- a/drivers/tty/serial/fsl_lpuart.c +++ b/drivers/tty/serial/fsl_lpuart.c @@ -2330,15 +2330,19 @@ lpuart32_set_termios(struct uart_port *port, struct ktermios *termios, /* update the per-port timeout */ uart_update_timeout(port, termios->c_cflag, baud);
+ /* + * disable CTS to ensure the transmit engine is not blocked by the flow + * control when there is dirty data in TX FIFO + */ + lpuart32_write(port, modem & ~UARTMODIR_TXCTSE, UARTMODIR); + /* * LPUART Transmission Complete Flag may never be set while queuing a break * character, so skip waiting for transmission complete when UARTCTRL_SBK is * asserted. */ - if (!(old_ctrl & UARTCTRL_SBK)) { - lpuart32_write(port, 0, UARTMODIR); + if (!(old_ctrl & UARTCTRL_SBK)) lpuart32_wait_bit_set(port, UARTSTAT, UARTSTAT_TC); - }
/* disable transmit and receive */ lpuart32_write(port, old_ctrl & ~(UARTCTRL_TE | UARTCTRL_RE), @@ -2346,8 +2350,6 @@ lpuart32_set_termios(struct uart_port *port, struct ktermios *termios,
lpuart32_write(port, bd, UARTBAUD); lpuart32_serial_setbrg(sport, baud); - /* disable CTS before enabling UARTCTRL_TE to avoid pending idle preamble */ - lpuart32_write(port, modem & ~UARTMODIR_TXCTSE, UARTMODIR); /* restore control register */ lpuart32_write(port, ctrl, UARTCTRL); /* re-enable the CTS if needed */