linux-kernel - Re: [PATCH 00/11] drivers: Add Pinctrl PM support

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Date:	Fri, 31 May 2013 10:04:37 -0700
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	Hebbar Gururaja <gururaja.hebbar@...com>
Cc:	khilman@...aro.org, grant.likely@...aro.org,
	linus.walleij@...aro.org, rob.herring@...xeda.com,
	davinci-linux-open-source@...ux.davincidsp.com,
	devicetree-discuss@...ts.ozlabs.org,
	linux-arm-kernel@...ts.infradead.org, linux@....linux.org.uk,
	linux-kernel@...r.kernel.org, vaibhav.bedia@...com,
	sudhakar.raj@...com
Subject: Re: [PATCH 00/11] drivers: Add Pinctrl PM support

Hi Hebbar,

On Fri, May 31, 2013 at 03:43:00PM +0530, Hebbar Gururaja wrote:
> By optionally putting the pins into sleep state in the suspend [or in
> runtime_suspend] callback we can accomplish two things.
> - One is to minimize current leakage from pins and thus save power,
> - second, we can prevent the IP from driving pins output in an
> uncontrolled manner, which may happen if the power domain drops the
> domain regulator.
> 
> These states can be specified in the DT blob and corresponding driver
> can pick these states during probe & set the related values during
> idle/suspend.
> 
> Not all drivers support/has idle state. Drivers like i2c, spi, mmc has
> idle states and hence these drivers are updated to support all the
> three states
> - default  : during regular operation
> - idle : when the module is in idle state
> - sleep : when the module is in suspend state
> 
> For those drivers which doesn't support/have idle state (at least at
> the moment), only default & sleep state is added.

As with the original introduction of pinctrl states my question is: "Can
all of this be handled in the driver/bus core instead of adding a lot
of boilerplate code to the individual drivers".

Thanks.

-- 
Dmitry
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