linux-kernel - Re: [PATCHv3 2/5] driver: serial: omap: prevent runtime PM for "no_console

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Date:	Thu, 25 Apr 2013 10:58:03 +0530
From:	Sourav Poddar <sourav.poddar@...com>
To:	Kevin Hilman <khilman@...aro.org>
CC:	<gregkh@...uxfoundation.org>, <tony@...mide.com>,
	<rmk+kernel@....linux.org.uk>, <linux-serial@...r.kernel.org>,
	<linux-omap@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCHv3 2/5] driver: serial: omap: prevent runtime PM for "no_console_suspend"

Hi Kevin,
On Thursday 25 April 2013 03:04 AM, Kevin Hilman wrote:
> Sourav Poddar<sourav.poddar@...com>  writes:
>
>> The driver manages "no_console_suspend" by preventing runtime PM
>> during the suspend path, which forces the console UART to stay awake.
>>
>> Signed-off-by: Sourav Poddar<sourav.poddar@...com>
>> ---
>>   drivers/tty/serial/omap-serial.c |   29 ++++++++++++++++++++++++++++-
>>   1 files changed, 28 insertions(+), 1 deletions(-)
>>
>> diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
>> index 08332f3..468e7ad 100644
>> --- a/drivers/tty/serial/omap-serial.c
>> +++ b/drivers/tty/serial/omap-serial.c
>> @@ -161,6 +161,7 @@ struct uart_omap_port {
>>   	u32			calc_latency;
>>   	struct work_struct	qos_work;
>>   	struct pinctrl		*pins;
>> +	bool			is_suspending;
>>   };
>>
>>   #define to_uart_omap_port(p)	((container_of((p), struct uart_omap_port, port)))
>> @@ -1278,6 +1279,24 @@ static struct uart_driver serial_omap_reg = {
>>   };
>>
>>   #ifdef CONFIG_PM_SLEEP
>> +static int serial_omap_prepare(struct device *dev)
>> +{
>> +	struct uart_omap_port *up = dev_get_drvdata(dev);
>> +
>> +	if (!console_suspend_enabled&&  uart_console(&up->port))
>> +		up->is_suspending = true;
> This flag should be set unconditionally.  IOW, the system is suspending
> independently of the values of those flags.  And then...
>
True. Will change.
>> +	return 0;
>> +}
>> +
>> +static void serial_omap_complete(struct device *dev)
>> +{
>> +	struct uart_omap_port *up = dev_get_drvdata(dev);
>> +
>> +	if (!console_suspend_enabled&&  uart_console(&up->port))
>> +		up->is_suspending = false;
>> +}
>> +
>>   static int serial_omap_suspend(struct device *dev)
>>   {
>>   	struct uart_omap_port *up = dev_get_drvdata(dev);
>> @@ -1296,7 +1315,10 @@ static int serial_omap_resume(struct device *dev)
>>
>>   	return 0;
>>   }
>> -#endif
>> +#else
>> +#define serial_omap_prepare NULL
>> +#define serial_omap_prepare NULL
>> +#endif /* CONFIG_PM_SLEEP */
>>
>>   static void omap_serial_fill_features_erratas(struct uart_omap_port *up)
>>   {
>> @@ -1582,6 +1604,9 @@ static int serial_omap_runtime_suspend(struct device *dev)
>>   	struct uart_omap_port *up = dev_get_drvdata(dev);
>>   	struct omap_uart_port_info *pdata = dev->platform_data;
>>
>> +	if (up->is_suspending)
>> +		return -EBUSY;
> ... the console checks should be here.
>
Ok. will change.
>>   	if (!up)
>>   		return -EINVAL;
>>
>> @@ -1632,6 +1657,8 @@ static const struct dev_pm_ops serial_omap_dev_pm_ops = {
>>   	SET_SYSTEM_SLEEP_PM_OPS(serial_omap_suspend, serial_omap_resume)
>>   	SET_RUNTIME_PM_OPS(serial_omap_runtime_suspend,
>>   				serial_omap_runtime_resume, NULL)
>> +	.prepare        = serial_omap_prepare,
>> +	.complete       = serial_omap_complete,
>>   };
>>
>>   #if defined(CONFIG_OF)
> Kevin

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