linux-kernel - Re: [PATCHv2] arm: mach-omap2: prevent UART console idle on suspend while using "no_console

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Date:	Tue, 2 Apr 2013 19:13:17 +0530
From:	Sourav Poddar <sourav.poddar@...com>
To:	Michael Trimarchi <michael@...rulasolutions.com>
CC:	<tony@...mide.com>, <khilman@...aro.org>,
	<rmk+kernel@....linux.org.uk>, <gregkh@...uxfoundation.org>,
	<linux-serial@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-omap@...r.kernel.org>, <b-cousson@...com>,
	Santosh Shilimkar <santosh.shilimkar@...com>,
	Felipe Balbi <balbi@...com>, Rajendra nayak <rnayak@...com>
Subject: Re: [PATCHv2] arm: mach-omap2: prevent UART console idle on suspend
 while using "no_console_suspend"

Hi,
On Tuesday 02 April 2013 07:04 PM, Michael Trimarchi wrote:
> Hi
>
> On 02/04/13 15:28, Sourav Poddar wrote:
>> With dt boot, uart wakeup after suspend is non functional while using
>> "no_console_suspend" in the bootargs. With "no_console_suspend" used, od->flags
>> should be ORed with "OMAP_DEVICE_NO_IDLE_ON_SUSPEND", thereby not allowing the console
>> to idle in the suspend path.
>>
>> Tested on omap5430evm, omap4430sdp.
>>
>> Cc: Santosh Shilimkar<santosh.shilimkar@...com>
>> Cc: Felipe Balbi<balbi@...com>
>> Cc: Rajendra nayak<rnayak@...com>
>> Signed-off-by: Sourav Poddar<sourav.poddar@...com>
>> ---
>> v1->v2
>> These patches were sent before as a series[1], but realised
>> "core_initcall(omap_serial_early_init)" in serial.c get executed
>> irrespective of dt or non dt boot and it will do most of the stuff
>> for us.
>> As suggested by Kevin Hilman in the previous version, this patch will
>> also prevent creating dependency between omap_device
>> (generic device-independent code) and a specific driver (UART).
>>
>> [1]: http://lkml.org/lkml/2013/3/18/294
>>
>>   arch/arm/mach-omap2/omap_device.c |    5 +++--
>>   arch/arm/mach-omap2/omap_hwmod.h  |    5 +++++
>>   arch/arm/mach-omap2/serial.c      |    4 +++-
>>   3 files changed, 11 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/arm/mach-omap2/omap_device.c b/arch/arm/mach-omap2/omap_device.c
>> index 381be7a..89be64d 100644
>> --- a/arch/arm/mach-omap2/omap_device.c
>> +++ b/arch/arm/mach-omap2/omap_device.c
>> @@ -170,8 +170,9 @@ static int omap_device_build_from_dt(struct platform_device *pdev)
>>   			r->name = dev_name(&pdev->dev);
>>   	}
>>
>> -	if (of_get_property(node, "ti,no_idle_on_suspend", NULL))
>> -		omap_device_disable_idle_on_suspend(pdev);
>> +	if (oh->flags&  HWMOD_DISABLE_IDLE_ON_SUSPEND ||
>> +		of_get_property(node, "ti,no_idle_on_suspend", NULL))
>> +			omap_device_disable_idle_on_suspend(pdev);
>>
>>   	pdev->dev.pm_domain =&omap_device_pm_domain;
>>
>> diff --git a/arch/arm/mach-omap2/omap_hwmod.h b/arch/arm/mach-omap2/omap_hwmod.h
>> index d43d9b6..50e6145 100644
>> --- a/arch/arm/mach-omap2/omap_hwmod.h
>> +++ b/arch/arm/mach-omap2/omap_hwmod.h
>> @@ -459,6 +459,10 @@ struct omap_hwmod_omap4_prcm {
>>    *     correctly, or this is being abused to deal with some PM latency
>>    *     issues -- but we're currently suffering from a shortage of
>>    *     folks who are able to track these issues down properly.
>> + * HWMOD_DISABLE_IDLE_ON_SUSPEND: don't idle this module on suspend. This is
>> + *     needed for uart controller, which requires its clock not to be cut
>> + *     during suspend while using "no_console_suspend" in bootargs with
>> + *     device tree boot.
>>    */
>>   #define HWMOD_SWSUP_SIDLE			(1<<  0)
>>   #define HWMOD_SWSUP_MSTANDBY			(1<<  1)
>> @@ -471,6 +475,7 @@ struct omap_hwmod_omap4_prcm {
>>   #define HWMOD_16BIT_REG				(1<<  8)
>>   #define HWMOD_EXT_OPT_MAIN_CLK			(1<<  9)
>>   #define HWMOD_BLOCK_WFI				(1<<  10)
>> +#define HWMOD_DISABLE_IDLE_ON_SUSPEND		(1<<  12)
> Just a comment more. Why 12 and not 11?
>
My Bad. For testing, developed it on an internal tree where 11 was also 
occupied. While
rebasing it on 3.9-rc5, didn't realise 11 is free.
Will fix it in the next version.

Thanks,
Sourav
> Michael
>
>>
>>   /*
>>    * omap_hwmod._int_flags definitions
>> diff --git a/arch/arm/mach-omap2/serial.c b/arch/arm/mach-omap2/serial.c
>> index 8396b5b..adbafbd 100644
>> --- a/arch/arm/mach-omap2/serial.c
>> +++ b/arch/arm/mach-omap2/serial.c
>> @@ -236,8 +236,10 @@ static int __init omap_serial_early_init(void)
>>   					uart_name, uart->num);
>>   			}
>>
>> -			if (cmdline_find_option("no_console_suspend"))
>> +			if (cmdline_find_option("no_console_suspend")) {
>>   				no_console_suspend = true;
>> +				oh->flags |= HWMOD_DISABLE_IDLE_ON_SUSPEND;
>> +			}
>>
>>   			/*
>>   			 * omap-uart can be used for earlyprintk logs
>>
> --
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