Commit cc994bb9 authored by Tony Lindgren's avatar Tony Lindgren Committed by Greg Kroah-Hartman
Browse files

serial: 8250: Fix runtime PM for start_tx() for empty buffer 



Commit 932d5963 ("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: 932d5963 ("serial: 8250: Return early in .start_tx() if there are no chars to send")
Cc: Steffen Trumtrar <s.trumtrar@pengutronix.de>
Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: default avatarJohan Hovold <johan@kernel.org>
Reviewed-by: default avatarUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: default avatarTony Lindgren <tony@atomide.com>
Link: https://lore.kernel.org/r/20220411111657.16744-1-tony@atomide.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 3ee82c6e

drivers/tty/serial/8250/8250_port.c

+2 −2
Original line number Diff line number Diff line
@@ -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;