linux-kernel - Re: [PATCHv4] serial: of-serial: fix up PM ops on no_console

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Message-ID: <543E1730.2040108@nvidia.com>
Date:	Wed, 15 Oct 2014 14:41:52 +0800
From:	Joseph Lo <josephl@...dia.com>
To:	Jingchang Lu <jingchang.lu@...escale.com>,
	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>
CC:	"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: [PATCHv4] serial: of-serial: fix up PM ops on no_console_suspend
 and port type

On 10/15/2014 02:32 PM, Jingchang Lu wrote:
>> -----Original Message-----
>> From: Joseph Lo [mailto:josephl@...dia.com]
>> Sent: Wednesday, October 15, 2014 9:01 AM
>> To: Lu Jingchang-B35083; gregkh@...uxfoundation.org
>> Cc: peter@...leysoftware.com; arnd@...db.de; linux-kernel@...r.kernel.org;
>> linux-serial@...r.kernel.org; linux-arm-kernel@...ts.infradead.org
>> Subject: Re: [PATCHv4] serial: of-serial: fix up PM ops on
>> no_console_suspend and port type
>>
>> On 10/14/2014 04:42 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>
>>
>> If you can make sure this patch can build without include
>> <linux/console.h>, then this patch
> The build passes on my cloned linux-next tree, include next-20141014,
> but is required on my another kernel-3.12+ based tree, then I didn't
> add this header file when upstream.
> Is the build broken on your source tree, and is the tree latest?
> If the header is needed, I will add it.
I tested it on next-20141013 and k3.14, both of them need the fix. I can 
check it again against the latest linux-next tree later. Thanks.

-Joseph

> Thanks.
>
> Best Regards,
> Jingchang
>>
>> Tested-by: Joseph Lo <josephl@...dia.com>
>>
>> And thanks for your fix.
>>
>>> ---
>>> 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.
>>>
>>>    drivers/tty/serial/of_serial.c | 52
>> ++++++++++++++++++++++++++++++++++++------
>>>    1 file changed, 45 insertions(+), 7 deletions(-)
>>>
>>> diff --git a/drivers/tty/serial/of_serial.c
>>> b/drivers/tty/serial/of_serial.c index 8bc2563..5281f8f 100644
>>> --- a/drivers/tty/serial/of_serial.c
>>> +++ b/drivers/tty/serial/of_serial.c
>>> @@ -241,13 +241,48 @@ 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 +291,13 @@ 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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