linux-kernel - Re: [PATCH] serial: 8250_omap: Fix errors with no_console

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Date:   Tue, 26 Sep 2023 17:02:41 +0530
From:   Dhruva Gole <d-gole@...com>
To:     Thomas Richard <thomas.richard@...tlin.com>
CC:     Tony Lindgren <tony@...mide.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        Andy Shevchenko <andriy.shevchenko@...el.com>,
        Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
        John Ogness <john.ogness@...utronix.de>,
        Johan Hovold <johan@...nel.org>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Vignesh Raghavendra <vigneshr@...com>,
        <linux-kernel@...r.kernel.org>, <linux-serial@...r.kernel.org>,
        Udit Kumar <u-kumar1@...com>
Subject: Re: [PATCH] serial: 8250_omap: Fix errors with no_console_suspend

On Sep 26, 2023 at 09:51:30 +0200, Thomas Richard wrote:
> Hi Tony,
> 
> Thanks for the fix.
> 
> On 9/26/23 08:13, Tony Lindgren wrote:
> > We now get errors on system suspend if no_console_suspend is set as
> > reported by Thomas. The errors started with commit 20a41a62618d ("serial:
> > 8250_omap: Use force_suspend and resume for system suspend").
> > 
> > Let's fix the issue by checking for console_suspend_enabled in the system
> > suspend and resume path.
> > 
> > Note that with this fix the checks for console_suspend_enabled in
> > omap8250_runtime_suspend() become useless. We now keep runtime PM usage
> > count for an attached kernel console starting with commit bedb404e91bb
> > ("serial: 8250_port: Don't use power management for kernel console").
> > 
> > Fixes: 20a41a62618d ("serial: 8250_omap: Use force_suspend and resume for system suspend")
> > Cc: Udit Kumar <u-kumar1@...com>
> > Reported-by: Thomas Richard <thomas.richard@...tlin.com>

Don't we want a closes: tag?

> > Signed-off-by: Tony Lindgren <tony@...mide.com>
> 
> Tested-by: Thomas Richard <thomas.richard@...tlin.com>

Thanks for testing Thomas

> 
> > ---
> >  drivers/tty/serial/8250/8250_omap.c | 25 ++++++++++---------------
> >  1 file changed, 10 insertions(+), 15 deletions(-)
> > 
> > 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
> > @@ -1617,7 +1617,7 @@ static int omap8250_suspend(struct device *dev)
> >  {
> >  	struct omap8250_priv *priv = dev_get_drvdata(dev);
> >  	struct uart_8250_port *up = serial8250_get_port(priv->line);
> > -	int err;
> > +	int err = 0;
> >  
> >  	serial8250_suspend_port(priv->line);
> >  
> > @@ -1627,7 +1627,8 @@ static int omap8250_suspend(struct device *dev)
> >  	if (!device_may_wakeup(dev))
> >  		priv->wer = 0;
> >  	serial_out(up, UART_OMAP_WER, priv->wer);
> > -	err = pm_runtime_force_suspend(dev);
> > +	if (uart_console(&up->port) && console_suspend_enabled)
> > +		err = pm_runtime_force_suspend(dev);
> >  	flush_work(&priv->qos_work);
> >  
> >  	return err;
> > @@ -1636,11 +1637,15 @@ static int omap8250_suspend(struct device *dev)
> >  static int omap8250_resume(struct device *dev)
> >  {
> >  	struct omap8250_priv *priv = dev_get_drvdata(dev);
> > +	struct uart_8250_port *up = serial8250_get_port(priv->line);
> >  	int err;
> >  
> > -	err = pm_runtime_force_resume(dev);
> > -	if (err)
> > -		return err;
> > +	if (uart_console(&up->port) && console_suspend_enabled) {
> > +		err = pm_runtime_force_resume(dev);
> > +		if (err)
> > +			return err;
> > +	}

LGTM, thanks for the fix Tony.

Reviewed-by: Dhruva Gole <d-gole@...com>

> > +
> >  	serial8250_resume_port(priv->line);
> >  	/* Paired with pm_runtime_resume_and_get() in omap8250_suspend() */
> >  	pm_runtime_mark_last_busy(dev);
> > @@ -1717,16 +1722,6 @@ static int omap8250_runtime_suspend(struct device *dev)
> >  
> >  	if (priv->line >= 0)
> >  		up = serial8250_get_port(priv->line);
> > -	/*
> > -	 * When using 'no_console_suspend', the console UART must not be
> > -	 * suspended. Since driver suspend is managed by runtime suspend,
> > -	 * preventing runtime suspend (by returning error) will keep device
> > -	 * active during suspend.
> > -	 */
> > -	if (priv->is_suspending && !console_suspend_enabled) {
> > -		if (up && uart_console(&up->port))
> > -			return -EBUSY;
> > -	}
> >  
> >  	if (priv->habit & UART_ERRATA_CLOCK_DISABLE) {
> >  		int ret;
> -- 
> Thomas Richard
> 

-- 
Best regards,
Dhruva Gole <d-gole@...com>