Re: PROBLEM: Sun Ultra 60 hangs on boot since Linux 6.8

[Tony Lindgren]

Hi,

* Nick Bowler <nbowler@xxxxxxxxxx> [240322 04:29]:
> I bisected to this commit:
> 
>   commit 45a3a8ef81291b63a2b50a1a145857dd9fc05e89
>   Author: Tony Lindgren <tony@xxxxxxxxxxx>
>   Date:   Mon Nov 13 10:07:53 2023 +0200
>   
>       serial: core: Revert checks for tx runtime PM state
> 
> Reverting this commit on top of Linux 6.8 is sufficient to get the
> system booting again.

Thanks a lot for bisecting and reporting the issue.

Can you please test if the following change to add back the check for
!pm_runtime_active() is enough to fix the issue?

Regards,

Tony

8< -----------------------
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -156,7 +156,7 @@ static void __uart_start(struct uart_state *state)
 	 * enabled, serial_port_runtime_resume() calls start_tx() again
 	 * after enabling the device.
 	 */
-	if (pm_runtime_active(&port_dev->dev))
+	if (!pm_runtime_enabled(&port_dev->dev) || pm_runtime_active(&port_dev->dev))
 		port->ops->start_tx(port);
 	pm_runtime_mark_last_busy(&port_dev->dev);
 	pm_runtime_put_autosuspend(&port_dev->dev);
-- 
2.44.0