linux-kernel - RE: [PATCH] i2c/tegra: I2C driver uses the suspend_noirq/resume

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Message-ID: <74CDBE0F657A3D45AFBB94109FB122FF04B24A3CA6@HQMAIL01.nvidia.com>
Date:	Wed, 24 Aug 2011 14:28:29 -0700
From:	Stephen Warren <swarren@...dia.com>
To:	Mark Brown <broonie@...nsource.wolfsonmicro.com>,
	Colin Cross <ccross@...gle.com>
CC:	Ben Dooks <ben-linux@...ff.org>, Dilan Lee <dilee@...dia.com>,
	"linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
	"linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] i2c/tegra: I2C driver uses the
 suspend_noirq/resume_noirq

Mark Brown wrote at Thursday, August 11, 2011 9:15 PM:
> On Thu, Aug 11, 2011 at 07:59:27PM -0700, Colin Cross wrote:
> > On Thu, Aug 11, 2011 at 5:45 PM, Mark Brown
> 
> > > For example with ASoC we'd sort all the components before the ASoC card
> > > without regard for their bus dependencies or any other dependencies they
> > > have (eg, their regulators). Since the ASoC card is a platform device
> > > it's likely to have registered early with no regard for where the buses
> > > the card needs are registered. I'd expect there's a reasonable chance
> > > it'll actually make things worse in the short term.
> 
> > You can't just move everything after the card, you have to move
> > everything after the last device that was probed, and it only works if
> > nothing depends on any of the devices that are moved.
> 
> Sorry, I said that the wrong way round due to trying to reply quickly -
> the card would be the thing that moves since that's the thing that
> actually does the suspend but we've *no* idea which device we need to
> move it after.  Since all the function does is a direct move after or
> before a single device all we can do is pick one and pray that it's the
> right device.

Colin, 

This thread seems to have died down; how should we make progress?

It sounds like the suspend_irq solution is the current de-facto standard;
not optimal, but all we really have right now and already in use. I could
certainly see avoiding this solution if it was the first time it was
employed, but re-using it seems reasonable to me?

Alternatively, are you attending either Linux Plumbers Conference or the
Kernel Summit? Mark implied this topic might well come up for discussion
there. Unfortunately, I won't be able to make LPC due to a conflict.

(and you'd mentioned having the subsystem maintainers weigh in on this;
which sub-system; IRQ, power, I2C, ...?)

Thanks!

-- 
nvpublic

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