linux-kernel - Re: [PATCH 2/2] ARM: dts: exynos4412-trats: Add suspend configuration for max77686 regulators

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Date:	Tue, 21 Oct 2014 12:14:36 +0200
From:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
To:	Javier Martinez Canillas <javier.martinez@...labora.co.uk>
Cc:	Chanwoo Choi <cw00.choi@...sung.com>,
	Ben Dooks <ben-linux@...ff.org>,
	Kukjin Kim <kgene.kim@...sung.com>,
	Russell King <linux@....linux.org.uk>,
	Liam Girdwood <lgirdwood@...il.com>,
	Mark Brown <broonie@...nel.org>,
	linux-arm-kernel@...ts.infradead.org,
	linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
	Kyungmin Park <kyungmin.park@...sung.com>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
	Tomasz Figa <tomasz.figa@...il.com>
Subject: Re: [PATCH 2/2] ARM: dts: exynos4412-trats: Add suspend configuration
 for max77686 regulators

On wto, 2014-10-21 at 12:00 +0200, Javier Martinez Canillas wrote:
> Hello Krzysztof,
> 
> On 10/21/2014 11:23 AM, Krzysztof Kozlowski wrote:
> >> >  
> >> >  				ldo9_reg: ldo9 {
> >> > @@ -295,7 +311,9 @@
> >> >  					regulator-name = "CAM_ISP_MIPI_1.2V";
> >> >  					regulator-min-microvolt = <1200000>;
> >> >  					regulator-max-microvolt = <1200000>;
> >> > -					regulator-mem-idle;
> >> > +					regulator-state-mem {
> >> > +						regulator-on-in-suspend;
> >> 
> >> CAM_ISP_MIPI_1.2V is used for camera, I think this regulator should turn off in suspend state
> >> because camear could not be used in suspend state.
> > 
> > LDO9 does not support off in suspend mode controlled by PWRREQ. It
> > supports only switching to low power mode if PWRREQ level goes low.
> > 
> > Thus the driver does not provide set_suspend_enable or
> > set_suspend_disable for LDO0. Do you want to add such function to the
> > max77686 driver which will explicitly disable the regulator (write 0x0
> > to control reg)?
> > 
> > 
> 
> I think for those regulators you can just use regulator_disable_regmap()
> as the .set_suspend_disable function handler?

Sure... but this does not solve the philosophical problem - this is not
a special suspend configuration. It is disabling the regulator manually,
from regulator core code. Instead probably the camera driver should
disable the regulator in suspend callback.

Another point - I think none of other regulators do this way.

Best regards,
Krzysztof


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