linux-kernel - Re: [PATCH 2/3] regulator: s2mps11: Add set_suspend

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Date:	Fri, 07 Mar 2014 11:15:10 +0100
From:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
To:	Mark Brown <broonie@...nel.org>
Cc:	Sangbeom Kim <sbkim73@...sung.com>,
	Liam Girdwood <lgirdwood@...il.com>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	Lee Jones <lee.jones@...aro.org>, linux-kernel@...r.kernel.org,
	linux-samsung-soc@...r.kernel.org,
	Kyungmin Park <kyungmin.park@...sung.com>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
	Tomasz Figa <t.figa@...sung.com>,
	Yadwinder Singh Brar <yadi.brar@...sung.com>,
	Sachin Kamat <sachin.kamat@...aro.org>
Subject: Re: [PATCH 2/3] regulator: s2mps11: Add set_suspend_disable for S2MPS14

On Fri, 2014-03-07 at 10:37 +0800, Mark Brown wrote:
> On Thu, Mar 06, 2014 at 03:42:22PM +0100, Krzysztof Kozlowski wrote:
> 
> > However in that case the driver won't be able later to change that value
> > back to "normal enable" (enable_mask). Consider such flow:
> > 1. System is going to suspend.
> > 2. Some regulator has "rstate->disabled" so set_suspend_disable() is
> > called on it.
> > 3. The "suspend" value is written to the device for given regulator and
> > it is stored as "enable" value.
> > 4. If regulator is enabled during here then the same "suspend" value
> > will be written.
> > 5. System is suspended.
> > 6. After resuming regulator_suspend_finish() calls
> > _regulator_do_enable() on the regulator... which will write the
> > "suspend" value because the driver cannot differentiate between this
> > enable and previous.
> 
> > I assume that this may not be a problem because:
> > 1. Regulator will be still turned on (the "suspend" value tells PMIC to
> > enable the regulator when SoC enables power).
> > 2. The first disable of regulator may bring back "enable" value back to
> > normal mode.
> 
> > Am I thinking here correctly? 
> 
> I'm not entirely sure I follow here.  Why would a disable reset the
> enable value?  My understanding is that this is a bitfield with several
> values, off, on always and on when they system is active.  The suspend
> state is being tracked with a variable so I'm not sure why disabling
> would reset it?
> 
> There is a bit of an issue if the regulator is disabled during runtime
> but enabled in suspend but that's hard to resolve and I'm not sure that
> it's a realistic issue.

OK, I think I understand it... I sent v2 of the set_suspend_disable
patch.

Best regards,
Krzysztof


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