linux-kernel - Re: [lm-sensors] regulator: regulator_get behaviour without CONFIG

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Message-ID: <1270567639.3229.56.camel@odin>
Date:	Tue, 06 Apr 2010 16:27:19 +0100
From:	Liam Girdwood <lrg@...mlogic.co.uk>
To:	Jean Delvare <khali@...ux-fr.org>
Cc:	Jerome Oufella <jerome.oufella@...oirfairelinux.com>,
	lm-sensors <lm-sensors@...sensors.org>,
	linux-kernel@...r.kernel.org,
	Mark Brown <broonie@...nsource.wolfsonmicro.com>
Subject: Re: [lm-sensors] regulator: regulator_get behaviour without
 CONFIG_REGULATOR set

On Mon, 2010-04-05 at 14:23 +0100, Mark Brown wrote:
> On Sat, Apr 03, 2010 at 05:37:45PM +0200, Jean Delvare wrote:
> > On Fri, 2 Apr 2010 21:45:03 +0100, Mark Brown wrote:
> 
> > > In this case you don't need the if (voltage) check - the code that uses
> > > supply_uV is going to have to cope with it being set to 0 if the driver
> > > doesn't just give up, and the enable wants to happen anyway (perhaps
> > > we've got a switchable supply we can't read the voltage of).  It should
> > > never make any odds if the notifier never gets called since the supply
> > > could be invariant.
> 
> > We still need to check if (voltage) to not overwrite the previous value
> > of data->supply_uV with 0. We will probably do that as an immediate fix
> > to the sht15 driver. But yes, the rest doesn't need a condition.
> 
> I was assuming that there wasn't a previous value since this was in
> probe(), sorry.
> 
> > Still, I'd prefer if drivers were just able to check for data->reg ==
> > NULL and skip the whole thing. Would you apply the following patch?
> 
> > From: Jean Delvare <khali@...ux-fr.org>
> > Subject: regulator: Let drivers know when they use the stub API
> 
> > Have the stub variant of regulator_get() return NULL, so that drivers
> > can (but still don't have to) handle this case specifically.
> 
> I guess I'll ack it but I'd be suspicous of driver code which actually
> makes use of this - there is actual hardware which has the same features
> as the regulator that gets stubbed in and ought to be handled.  On the
> other hand, perhaps someone will come up with a good use for it.
> 
> It also seems a bit odd to return a traditional error value in a success
> case but it doesn't actually make much difference.

Thanks, I've applied this with Mark's Ack.

I suppose this is something we may look into more when we have more
clients.

Liam

-- 
Freelance Developer, SlimLogic Ltd
ASoC and Voltage Regulator Maintainer.
http://www.slimlogic.co.uk

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