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Message-ID: <193a134c-f0da-4a45-b45a-a3605f91cfa4@draconx.ca>
Date: Fri, 22 Mar 2024 10:12:25 -0400
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Subject: Re: PROBLEM: Sun Ultra 60 hangs on boot since Linux 6.8
To: Tony Lindgren <tony@atomide.com>
Cc: linux-kernel@vger.kernel.org, sparclinux@vger.kernel.org,
 regressions@lists.linux.dev, linux-serial@vger.kernel.org
References: <d84baa5d-a092-3647-8062-ed7081d329d4@draconx.ca>
 <20240322051531.GA5132@atomide.com>
 <d7337014-09ac-8a35-7159-e75ecd2707b6@draconx.ca>
 <20240322064843.GC5132@atomide.com> <20240322090657.GD5132@atomide.com>
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From: Nick Bowler <nbowler@draconx.ca>
In-Reply-To: <20240322090657.GD5132@atomide.com>
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On 2024-03-22 05:06, Tony Lindgren wrote:
[...]
> I can't reproduce this on qemu-system-sparc64, probably as it does not use
> the sunsab driver.
> 
> I noticed something though, I think we need to test for the port device
> instead for being runtime PM enabled.
> 
> Can you please test if the updated patch below make things work again?

Yes, with the below patch applied on top of 6.8 things are working.

Thanks,
  Nick

> 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) || 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)