linux-kernel - Re: [PATCHv5] serial: of-serial: fix up PM ops on no_console

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Date:	Wed, 15 Oct 2014 17:02:44 +0800
From:	Joseph Lo <josephl@...dia.com>
To:	Jingchang Lu <jingchang.lu@...escale.com>,
	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>
CC:	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"peter@...leysoftware.com" <peter@...leysoftware.com>,
	"arnd@...db.de" <arnd@...db.de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCHv5] serial: of-serial: fix up PM ops on no_console_suspend
 and port type

On 10/15/2014 02:19 PM, Jingchang Lu wrote:
> This patch fixes commit 2dea53bf57783f243c892e99c10c6921e956aa7e,
> "serial: of-serial: add PM suspend/resume support", which disables
> the uart clock on suspend, but also causes a hardware hang on register
> access if no_console_suspend command line option is used.
>
> Also, not every of_serial device is an 8250 port, so the serial8250
> suspend/resume functions should only be applied to a real 8250 port.
>
> Signed-off-by: Jingchang Lu <jingchang.lu@...escale.com>
> ---
> changes in v5:
>   add missing <linux/console.h> include.
>
> changes in v4:
>   separate 8250 port suspend/resume from of_serial_suspend/resume.
>
> changes in v3:
>   fix up point reference and deference.
>
> changes in v2:
>   add switch selection on uart type.
>
Hi Jingchang,

Thanks for the fix. This patch
Tested-by: Joseph Lo <josephl@...dia.com>

>   drivers/tty/serial/of_serial.c | 53 ++++++++++++++++++++++++++++++++++++------
>   1 file changed, 46 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/tty/serial/of_serial.c b/drivers/tty/serial/of_serial.c
> index 8bc2563..9c64ad2 100644
> --- a/drivers/tty/serial/of_serial.c
> +++ b/drivers/tty/serial/of_serial.c
> @@ -9,6 +9,7 @@
>    *  2 of the License, or (at your option) any later version.
>    *
>    */
> +#include <linux/console.h>
>   #include <linux/module.h>
>   #include <linux/slab.h>
>   #include <linux/delay.h>
> @@ -241,13 +242,48 @@ static int of_platform_serial_remove(struct platform_device *ofdev)
>   }
>
>   #ifdef CONFIG_PM_SLEEP
> -static int of_serial_suspend(struct device *dev)
> +#ifdef CONFIG_SERIAL_8250
> +static void of_serial_suspend_8250(struct of_serial_info *info)
>   {
> -	struct of_serial_info *info = dev_get_drvdata(dev);
> +	struct uart_8250_port *port8250 = serial8250_get_port(info->line);
> +	struct uart_port *port = &port8250->port;
>
>   	serial8250_suspend_port(info->line);
> -	if (info->clk)
> +	if (info->clk && (!uart_console(port) || console_suspend_enabled))
>   		clk_disable_unprepare(info->clk);
> +}
> +
> +static void of_serial_resume_8250(struct of_serial_info *info)
> +{
> +	struct uart_8250_port *port8250 = serial8250_get_port(info->line);
> +	struct uart_port *port = &port8250->port;
> +
> +	if (info->clk && (!uart_console(port) || console_suspend_enabled))
> +		clk_prepare_enable(info->clk);
> +
> +	serial8250_resume_port(info->line);
> +}
> +#else
> +static inline void of_serial_suspend_8250(struct of_serial_info *info)
> +{
> +}
> +
> +static inline void of_serial_resume_8250(struct of_serial_info *info)
> +{
> +}
> +#endif
> +
> +static int of_serial_suspend(struct device *dev)
> +{
> +	struct of_serial_info *info = dev_get_drvdata(dev);
> +
> +	switch(info->type) {
> +	case PORT_8250 ... PORT_MAX_8250:
> +		of_serial_suspend_8250(info);
> +		break;
> +	default:
> +		break;
> +	}
>
>   	return 0;
>   }
> @@ -256,10 +292,13 @@ static int of_serial_resume(struct device *dev)
>   {
>   	struct of_serial_info *info = dev_get_drvdata(dev);
>
> -	if (info->clk)
> -		clk_prepare_enable(info->clk);
> -
> -	serial8250_resume_port(info->line);
> +	switch(info->type) {
> +	case PORT_8250 ... PORT_MAX_8250:
> +		of_serial_resume_8250(info);
> +		break;
> +	default:
> +		break;
> +	}
>
>   	return 0;
>   }
>
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