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

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Date:	Mon, 09 Jul 2012 14:19:40 +0900
From:	Jingoo Han <jg1.han@...sung.com>
To:	'Alex Courbot' <acourbot@...dia.com>
Cc:	'Thierry Reding' <thierry.reding@...onic-design.de>,
	'Sascha Hauer' <s.hauer@...gutronix.de>,
	'Stephen Warren' <swarren@...dotorg.org>,
	'Mark Brown' <broonie@...nsource.wolfsonmicro.com>,
	linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-fbdev@...r.kernel.org
Subject: RE: [PATCH] pwm-backlight: add regulator and GPIO support



> -----Original Message-----
> From: linux-fbdev-owner@...r.kernel.org [mailto:linux-fbdev-owner@...r.kernel.org] On Behalf Of Stephen
> Warren
> Sent: Friday, July 06, 2012 1:04 AM
> To: Alex Courbot
> Cc: Thierry Reding; Sascha Hauer; Mark Brown; linux-tegra@...r.kernel.org; linux-kernel@...r.kernel.org;
> linux-fbdev@...r.kernel.org
> Subject: Re: [PATCH] pwm-backlight: add regulator and GPIO support
> 
> On 07/05/2012 02:12 AM, Alex Courbot wrote:
> > On 07/05/2012 04:57 PM, Thierry Reding wrote:
> >> I agree. Non-DT platforms have always used the callbacks to execute this
> >> kind of code. As you've said before there are situations where it isn't
> >> just about setting a GPIO or enabling a regulator but it also requires a
> >> specific timing. Representing this in the platform data would become
> >> tedious.
> >
> > That will settle the whole issue then.
> >
> >> So I think for the DT case you can parse the power-on and power-off
> >> sequences directly and execute code based on it, while in non-DT cases
> >> the init and exit callbacks should be used instead. I think it even
> >> makes sense to reuse the platform data's init and exit functions in the
> >> DT case and implement the parser/interpreter within those.
> >
> > It totally makes sense indeed.
> 
> I don't agree here. It'd be best if non-DT and DT cases worked as
> similarly as possible. Relying on callbacks in one case and
> data-parsed-from-DT in the other isn't consistent with that. After all,
> in the DT case, you parse some data out of the DT and into some data
> structure. In the non-DT case, you can have that data structure passed
> in directly using platform data. Now, there's certainly a need to
> continue to support callbacks for backwards compatibility, at the very
> least temporarily before all clients are converted to the new model, but
> requiring different models rather than simply allowing it seems like a
> bad idea to me.

Hi Alex Courbot,

I couldn't agree with Stephen Warren more.
Could you support DT and non-DT case for backwards compatibility?

Best regards,
Jingoo Han

> 
> 
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