From: Sherry Sun Date: Fri, 7 Mar 2025 06:54:46 +0000 (+0800) Subject: tty: serial: lpuart: only disable CTS instead of overwriting the whole UARTMODIR... X-Git-Tag: v6.15-rc1~47^2~8 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=e98ab45ec5182605d2e00114cba3bbf46b0ea27f;p=thirdparty%2Fkernel%2Flinux.git tty: serial: lpuart: only disable CTS instead of overwriting the whole UARTMODIR register 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 Signed-off-by: Sherry Sun Link: https://lore.kernel.org/r/20250307065446.1122482-1-sherry.sun@nxp.com Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c index c8cc0a241fba4..33eeefa6fa8f8 100644 --- a/drivers/tty/serial/fsl_lpuart.c +++ b/drivers/tty/serial/fsl_lpuart.c @@ -2349,15 +2349,19 @@ 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), @@ -2365,8 +2369,6 @@ 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 */