linux-kernel - Re: [PATCH 08/15] genirq: Add runtime power management support for IRQ chips

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Message-ID: <56EFC848.6030301@nvidia.com>
Date:	Mon, 21 Mar 2016 10:09:12 +0000
From:	Jon Hunter <jonathanh@...dia.com>
To:	Grygorii Strashko <grygorii.strashko@...com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Jason Cooper <jason@...edaemon.net>,
	Marc Zyngier <marc.zyngier@....com>,
	Benoît Cousson <bcousson@...libre.com>,
	Tony Lindgren <tony@...mide.com>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Stephen Warren <swarren@...dotorg.org>,
	Thierry Reding <thierry.reding@...il.com>
CC:	Kevin Hilman <khilman@...nel.org>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Lars-Peter Clausen <lars@...afoo.de>,
	Linus Walleij <linus.walleij@...aro.org>,
	<linux-tegra@...r.kernel.org>, <linux-omap@...r.kernel.org>,
	<devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 08/15] genirq: Add runtime power management support for
 IRQ chips


On 18/03/16 17:52, Grygorii Strashko wrote:
> On 03/18/2016 04:56 PM, Jon Hunter wrote:
>>
>> On 18/03/16 14:40, Jon Hunter wrote:
>>> On 18/03/16 14:23, Grygorii Strashko wrote:
>>>> On 03/18/2016 02:27 PM, Jon Hunter wrote:
>>>>>
>>>>> On 18/03/16 11:11, Grygorii Strashko wrote:
>>
>> [snip]
>>
>>>> oh :( That will require updating of all drivers (and if it will be taken into account that
>>>> wakeup can be configured from sysfs + devm_ - it will be painful).
>>>
>>> Will it? I know that there are a few gpio chips that have some hacked
>>> ways to get around the PM issue, but I wonder how many drivers this
>>> really impacts. What sysfs entries are you referring too?
> 
> echo enabled > /sys/devices/platform/44000000.ocp/48020000.serial/tty/ttyS2/power/wakeup
> 
>>
>> Thinking about this some more, yes I guess it would impact all drivers
>> that use a gpio but don't use it for a wake-up. I could see that could
>> be a few drivers indeed.
> 
> yep. I've just tested it
> - gpio was requested through sysfs and configured as IRQ
> - do suspend
> 
> the same is if GPIO is requested as IRQ only and not configured as wakeup source 
> 
> [  319.669760] PM: late suspend of devices complete after 0.213 msecs
> [  319.671195] irq 191 has no wakeup set and has not been freed!
> [  319.673453] PM: noirq suspend of devices complete after 2.258 msecs
> 
> this is very minimal configuration - the regular one is at ~30-50 devices
> most of them will use IRQ and only ~10% are used as wakeup sources.

Then it is working as intended :-)

However, if this is too verbose for some irqchips, then as I mentioned
we can have a flag to avoid these messages.

Cheers
Jon