linux-kernel - Re: [RFD] voltage/current regulator consumer interface

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Message-ID: <49ED628A.4000505@compulab.co.il>
Date:	Tue, 21 Apr 2009 09:07:06 +0300
From:	Mike Rapoport <mike@...pulab.co.il>
To:	James Kosin <jkosin@...a.intcomgrp.com>
CC:	linux-kernel@...r.kernel.org, Mike Rapoport <mike@...pulab.co.il>
Subject: Re: [RFD] voltage/current regulator consumer interface



James Kosin wrote:
> Mike Rapoport wrote:
>> Hi,
>>
>> Recently there was a brief discussion on linux-arm-kernel list [1] about
>> controlling voltage regulator state in cases when there is no consumer device
>> for a particular regulator.
>>
>> I have some thoughts but I'd like to know people opinion before I start
>> implementation.
>>
>> Problem
>> -------
>> The regulator framework API provides ability to control the state of
>> voltage/current regulators from within the kernel. Usually the regulator
>> supplies power to a device and device driver or some hooks to the platform code
>> from the device driver manipulate the regulator state. However, the regulator
>> framework does not have userspace ABI that allows regulator state modifications.
>> Lack of this ABI prevents fine-grained control for power consumption of devices
>> such as GPS trancievers and GSM modems. Moreover, in SoC based systems it is
>> possible to switch on/off power to entire subsystem when it is not used.
>>
> 
> 
> I'd also ask the question, Why?
> If exposing to user space it leaves the possibility of damaging hardware
> or completely frying a board.

Suppose you have a handheld device with GPS transceiver. You would like to give
user the ability to switch the transceiver on and off.

> 
> James
> --
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-- 
Sincerely yours,
Mike.

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