Re: [PATCH] i2c-s3c2410: Add stub runtime power management

[Mark Brown <broonie-yzvPICuk2AATkU/dhu1WVueM+bqZidxxQQ4Iyu8u01E@public.gmane.org>]

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On Mon, Feb 13, 2012 at 11:31:39PM +0000, Ben Dooks wrote:
> On Sun, Jan 22, 2012 at 09:39:53PM +0000, Mark Brown wrote:

> > TBH I think most of the devices for which people are running these days
> > will be able to get some win from the system wide stuff - the WFI modes
> > aren't exactly the latest thing in hardware terms, it's just been a long
> > road to getting them supported.  Infrastructure like Mark's PM QoS work
> > and Raphael's PM domains work has really helped a lot here.

> The WFI stuff's been around for ages, and is generally just the core that
> is affected. The deep sleep options might be useful, so I don't see any
> reason not to do this. I also approve that it might allow people to shut
> down I2C units they're not using at the time to save power.

On the more recent devices they've got wider effects if you configure
the device to enter one of the lower power states on WFI - things will
break quite badly if you enter even SLEEP mode on s3c64xx right now for
example as we don't make sure things like the UARTs are quiesced enough.
The power savings are nice, though.

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