From cc994bb97587787b8f0c094a9bc6945d82075b1d Mon Sep 17 00:00:00 2001 From: Tony Lindgren Date: Mon, 11 Apr 2022 14:16:57 +0300 Subject: [PATCH] serial: 8250: Fix runtime PM for start_tx() for empty buffer MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Commit 932d596378b0 ("serial: 8250: Return early in .start_tx() if there are no chars to send") caused a regression where the drivers implementing runtime PM stopped idling. This is because serial8250_rpm_put_tx() is now unbalanced on early return, it normally gets called at __stop_tx(). Fixes: 932d596378b0 ("serial: 8250: Return early in .start_tx() if there are no chars to send") Cc: Steffen Trumtrar Cc: Uwe Kleine-König Reviewed-by: Johan Hovold Reviewed-by: Uwe Kleine-König Signed-off-by: Tony Lindgren Link: https://lore.kernel.org/r/20220411111657.16744-1-tony@atomide.com Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/8250/8250_port.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c index 318af6f136050..26f9330094bc8 100644 --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -1675,11 +1675,11 @@ static void serial8250_start_tx(struct uart_port *port) struct uart_8250_port *up = up_to_u8250p(port); struct uart_8250_em485 *em485 = up->em485; - serial8250_rpm_get_tx(up); - if (!port->x_char && uart_circ_empty(&port->state->xmit)) return; + serial8250_rpm_get_tx(up); + if (em485 && em485->active_timer == &em485->start_tx_timer) return; -- 2.30.2