linux-kernel - Re: [PATCH] pwm-backlight: add regulator and GPIO support

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Message-ID: <4FF4FDC0.8020405@nvidia.com>
Date:	Thu, 5 Jul 2012 11:36:48 +0900
From:	Alex Courbot <acourbot@...dia.com>
To:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
CC:	Sascha Hauer <s.hauer@...gutronix.de>,
	Thierry Reding <thierry.reding@...onic-design.de>,
	"linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-fbdev@...r.kernel.org" <linux-fbdev@...r.kernel.org>
Subject: Re: [PATCH] pwm-backlight: add regulator and GPIO support

On 07/05/2012 12:24 AM, Mark Brown wrote:
> On Thu, Jul 05, 2012 at 12:14:39AM +0900, Alex Courbot wrote:
>> On Wed 04 Jul 2012 10:00:56 PM JST, Sascha Hauer wrote:
>
>>> Also please be aware that using a regulator in the pwm backlight will
>>> instantly break all existing users. That's hardly your fault though.
>
>> Sorry, I don't see why. Could you elaborate on this?
>
> All existing machines will start failing during probe as they won't be
> able to find the regulator - you should ideally make sure everyone in
> mainline gets an appropriate regulator set up.

Oh, that is a mistake of mine then. Driver probe should continue if no 
regulator is declared (but should fail if some other error occured). I 
want to maintain backward compatibility with current users of the 
driver, so regulator/gpio specification should be optional.

Thanks for all the feedback people - I will come back with a new version 
that addresses the points highlighted and also allows power on/off 
sequences to be specified in the device tree.

Alex.
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