linux-kernel - Re: [PATCH] regulator: max8973: add regulator driver support

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Message-ID: <20121120004356.GC4483@opensource.wolfsonmicro.com>
Date:	Tue, 20 Nov 2012 09:43:58 +0900
From:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
To:	Guennadi Liakhovetski <g.liakhovetski@....de>
Cc:	Laxman Dewangan <ldewangan@...dia.com>, lrg@...com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] regulator: max8973: add regulator driver support

On Mon, Nov 19, 2012 at 11:52:42AM +0100, Guennadi Liakhovetski wrote:

> Thanks for submitting this driver! The notion of DVS regulators was new to 
> me, so, I checked http://www.ti.com/lit/an/sbva020/sbva020.pdf for a short 
> description. After that I had a look at a couple of existing DVS regulator 

Do you just mean regulators that have a quick voltage change ability/

> drivers in the tree. Well, I came to two conclusions so far: (1) The 
> current regulator API is not very well suitable for such regulators. I 
> would imagine, one would need two methods: for setting the "normal" and 
> the DVS voltage. Instead of this drivers are trying to be smart at 
> guessing, which voltage the user is trying to set now... (2) Drivers do 
> this in different ways and at least out of the 2 drivers I looked at both 
> have bugs and different ones at that. I'll send a separate email, 
> describing what I found suspicious in them.

The thing I'd like to see factored out here is the LRU mechanism,
otherwise I think the situation is pretty good.  Some of the older
devices should use a different scheme to modern ones as the hardware
they have to interoperate is different.

> Of course, all the above was just my DVS-newbie impression, which can very 
> well be absolutely wrong.
> 
> > 
> > Add regulator driver for this device.

*ALWAYS* delete irrelevant text when replying.

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