linux-kernel - Re: [PATCH] i2c: exynos5: Properly use the "noirq" variants of suspend/resume

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Message-ID: <7hwqcbs166.fsf@paris.lan>
Date:	Fri, 20 Jun 2014 14:48:01 -0700
From:	Kevin Hilman <khilman@...aro.org>
To:	Doug Anderson <dianders@...omium.org>
Cc:	Wolfram Sang <wsa@...-dreams.de>,
	Kukjin Kim <kgene.kim@...sung.com>,
	Tomasz Figa <tomasz.figa@...il.com>,
	Javier Martinez Canillas <javier.martinez@...labora.co.uk>,
	naveen krishna <ch.naveen@...sung.com>,
	Jingoo Han <jg1.han@...sung.com>,
	Jean Delvare <jdelvare@...e.de>, Simon Glass <sjg@...gle.com>,
	Paul Gortmaker <paul.gortmaker@...driver.com>,
	standby24x7@...il.com, Sachin Kamat <sachin.kamat@...aro.org>,
	"linux-i2c\@vger.kernel.org" <linux-i2c@...r.kernel.org>,
	"linux-arm-kernel\@lists.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	linux-samsung-soc <linux-samsung-soc@...r.kernel.org>,
	"linux-kernel\@vger.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] i2c: exynos5: Properly use the "noirq" variants of suspend/resume

Hi Doug,

Doug Anderson <dianders@...omium.org> writes:

> On Thu, Jun 19, 2014 at 11:43 AM, Kevin Hilman <khilman@...aro.org> wrote:
>> Doug Anderson <dianders@...omium.org> writes:
>>
>>> The original code for the exynos i2c controller registered for the
>>> "noirq" variants.  However during review feedback it was moved to
>>> SIMPLE_DEV_PM_OPS without anyone noticing that it meant we were no
>>> longer actually "noirq" (despite functions named
>>> exynos5_i2c_suspend_noirq and exynos5_i2c_resume_noirq).
>>>
>>> i2c controllers that might have wakeup sources on them seem to need to
>>> resume at noirq time so that the individual drivers can actually read
>>> the i2c bus to handle their wakeup.
>>
>> I suspect usage of the noirq variants pre-dates the existence of the
>> late/early callbacks in the PM core, but based on the description above,
>> I suspect what you actually want is the late/early callbacks.
>
> I think it actually really needs noirq.  ;)

Yes, it appears it does.   Objection withdrawn.

I just wanted to be sure because since the introduction of late/early,
the need for noirq should be pretty rare, but there certainly are needs.

<tangent> 
In this case though, the need for it has more to do with the
lack of a way for us to describe non parent-child device dependencies
than whether or not IRQs are enabled or not.
</tangent>

Kevin
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