linux-kernel - Re: [PATCH 4/4] pwm_backlight: Add support for the whole range of the PWM in DT mode

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Message-ID: <20130129100048.GB16746@avionic-0098.mockup.avionic-design.de>
Date:	Tue, 29 Jan 2013 11:00:48 +0100
From:	Thierry Reding <thierry.reding@...onic-design.de>
To:	Peter Ujfalusi <peter.ujfalusi@...com>
Cc:	Richard Purdie <rpurdie@...ys.net>,
	Grant Likely <grant.likely@...retlab.ca>,
	Rob Landley <rob@...dley.net>,
	Florian Tobias Schandinat <FlorianSchandinat@....de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	devicetree-discuss@...ts.ozlabs.org, linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-fbdev@...r.kernel.org
Subject: Re: [PATCH 4/4] pwm_backlight: Add support for the whole range of
 the PWM in DT mode

On Tue, Jan 22, 2013 at 02:39:56PM +0100, Peter Ujfalusi wrote:
> When booting with DT make it possible to use the whole range of the PWM when
> controlling the backlight in a same way it is possible when the kernel is
> booted in non DT mode.
> A new property "max-brightness-level" can be used to specify the maximum
> value the PWM can handle (time slots).
> DTS files can use either the "brightness-levels" or the "max-brightness-level"
> to configure the PWM.
> In case both of these properties exist the driver will prefer the
> "brightness-levels" over the "max-brightness-level".
> 
> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@...com>

I don't think this is a good idea. The brightness-levels property was
specifically introduced in order to have a more reasonable interface to
specify brightness levels.

As such, all uses of the non-DT max_brightness to be deprecated. It is
only kept for backwards compatibility with non-DT boards.

Thierry

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