Re: AM5749: tty serial 8250 omap driver crash

[Tony Lindgren <tony@atomide.com>]

Hi,

* Romain Naour <romain.naour@smile.fr> [220209 09:13]:
> Le 07/02/2022 à 09:04, Tony Lindgren a écrit :
> > Interesting, what's the exception you get with the -rt kernel? Is it an
> > unhandled external abort or something else?
> 
> "asynchronous external abort"

OK

> Maybe there is something wrong with the smart-standby or smart-idle feature in
> the UART IP ? I'm not sure.

Could be that too, but maybe it's as simple as the patch below. Care to
give it a try?

> Are you able to reproduce it ?
> Maybe on a IDK574 or a Beaglebone-AI board ?

Not sure why I'm not seeing this one with my test systems.. Have not tried
with the RT patches for a while though.

Regards,

Tony

8< -------
diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c
--- a/drivers/tty/serial/8250/8250_omap.c
+++ b/drivers/tty/serial/8250/8250_omap.c
@@ -163,6 +163,8 @@ static void omap8250_set_mctrl(struct uart_port *port, unsigned int mctrl)
 	struct omap8250_priv *priv = up->port.private_data;
 	u8 lcr;
 
+	pm_runtime_get_sync(port->dev);
+
 	serial8250_do_set_mctrl(port, mctrl);
 
 	if (!mctrl_gpio_to_gpiod(up->gpios, UART_GPIO_RTS)) {
@@ -179,6 +181,9 @@ static void omap8250_set_mctrl(struct uart_port *port, unsigned int mctrl)
 		serial_out(up, UART_EFR, priv->efr);
 		serial_out(up, UART_LCR, lcr);
 	}
+
+	pm_runtime_mark_last_busy(port->dev);
+	pm_runtime_put_autosuspend(port->dev);
 }
 
 /*