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Date: Fri, 22 Mar 2024 07:15:32 +0200
From: Tony Lindgren <tony@atomide.com>
To: Nick Bowler <nbowler@draconx.ca>
Cc: linux-kernel@vger.kernel.org, sparclinux@vger.kernel.org,
	regressions@lists.linux.dev, linux-serial@vger.kernel.org
Subject: Re: PROBLEM: Sun Ultra 60 hangs on boot since Linux 6.8
Message-ID: <20240322051531.GA5132@atomide.com>
References: <d84baa5d-a092-3647-8062-ed7081d329d4@draconx.ca>
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In-Reply-To: <d84baa5d-a092-3647-8062-ed7081d329d4@draconx.ca>

Hi,

* Nick Bowler <nbowler@draconx.ca> [240322 04:29]:
> I bisected to this commit:
> 
>   commit 45a3a8ef81291b63a2b50a1a145857dd9fc05e89
>   Author: Tony Lindgren <tony@atomide.com>
>   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