linux-kernel - Re: [PATCH] serial: port: Don't suspend if the port is still busy

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Date: Mon, 05 Feb 2024 09:53:05 +0106
From: John Ogness <john.ogness@...utronix.de>
To: Yicong Yang <yangyicong@...wei.com>, gregkh@...uxfoundation.org,
 jirislaby@...nel.org, tony@...mide.com, linux-kernel@...r.kernel.org,
 linux-serial@...r.kernel.org
Cc: andriy.shevchenko@...ux.intel.com, tglx@...utronix.de,
 yangyicong@...ilicon.com, linuxarm@...wei.com, prime.zeng@...ilicon.com,
 jonathan.cameron@...wei.com, fanghao11@...wei.com
Subject: Re: [PATCH] serial: port: Don't suspend if the port is still busy

On 2024-02-04, Yicong Yang <yangyicong@...wei.com> wrote:
> diff --git a/drivers/tty/serial/serial_port.c b/drivers/tty/serial/serial_port.c
> index 88975a4df306..60d1eec6b6b7 100644
> --- a/drivers/tty/serial/serial_port.c
> +++ b/drivers/tty/serial/serial_port.c
> @@ -46,8 +46,28 @@ static int serial_port_runtime_resume(struct device *dev)
>  	return 0;
>  }
>  
> +static int serial_port_runtime_suspend(struct device *dev)
> +{
> +	struct serial_port_device *port_dev = to_serial_base_port_device(dev);
> +	struct uart_port *port;
> +	unsigned long flags;
> +
> +	port = port_dev->port;
> +
> +	if (port->flags & UPF_DEAD)
> +		return 0;
> +
> +	spin_lock_irqsave(&port->lock, flags);
> +	if (__serial_port_busy(port))
> +		pm_request_resume(dev);
> +	spin_unlock_irqrestore(&port->lock, flags);

Please use the wrapper functions for the uart port lock:

uart_port_lock_irqsave()
uart_port_unlock_irqrestore()

John Ogness