| Message ID | 20220411111657.16744-1-tony@atomide.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [PATCHv2] serial: 8250: Fix runtime PM for start_tx() for empty buffer | expand |
On Mon, Apr 11, 2022 at 02:16:57PM +0300, Tony Lindgren wrote: > 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 <s.trumtrar@pengutronix.de> > Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> > Signed-off-by: Tony Lindgren <tony@atomide.com> > --- > > Changes since v1: > > - Call serial8250_rpm_get_tx() only after buffer empty test as suggested > by Uwe and Johan > > - Drop RS885 related patch for now, it needs to be investigated further > > --- > 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 > --- 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; Reviewed-by: Johan Hovold <johan@kernel.org>
On Mon, Apr 11, 2022 at 02:16:57PM +0300, Tony Lindgren wrote: > 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 <s.trumtrar@pengutronix.de> > Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> > Signed-off-by: Tony Lindgren <tony@atomide.com> Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Thanks for cleaning up behind me, Uwe
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c --- 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;
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 <s.trumtrar@pengutronix.de> Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Signed-off-by: Tony Lindgren <tony@atomide.com> --- Changes since v1: - Call serial8250_rpm_get_tx() only after buffer empty test as suggested by Uwe and Johan - Drop RS885 related patch for now, it needs to be investigated further --- drivers/tty/serial/8250/8250_port.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)