linux-kernel - Re: [PATCH v2] pwm-backlight: allow for non-increasing brightness levels

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Date:	Thu, 26 Sep 2013 13:03:06 +0300
From:	Tomi Valkeinen <tomi.valkeinen@...com>
To:	Mike Dunn <mikedunn@...sguy.com>, <thierry.reding@...il.com>
CC:	Richard Purdie <rpurdie@...ys.net>,
	Jingoo Han <jg1.han@...sung.com>,
	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
	Grant Likely <grant.likely@...aro.org>,
	Rob Herring <rob.herring@...xeda.com>,
	<linux-pwm@...r.kernel.org>, <linux-fbdev@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>,
	Robert Jarzmik <robert.jarzmik@...e.fr>,
	Marek Vasut <marex@...x.de>
Subject: Re: [PATCH v2] pwm-backlight: allow for non-increasing brightness
 levels

On 22/09/13 19:59, Mike Dunn wrote:
> Currently the driver assumes that the values specified in the
> brightness-levels device tree property increase as they are parsed from
> left to right.  But boards that invert the signal between the PWM output
> and the backlight will need to specify decreasing brightness-levels.
> This patch removes the assumption that the last element of the array is
> the maximum value, and instead searches the array for the maximum value
> and uses that in the duty cycle calculation.
> 
> Signed-off-by: Mike Dunn <mikedunn@...sguy.com>
> ---
> Changelog:
> v2: 
> - commit message reworded; correct line wrap used
> - 'max_level' variable renamed to 'scale'
> - loop counter variable type changed to unsigned int
> - value held in scale changed from array index to actual maximum level
> - blank lines added around loop for readability

As you said in a previous mail, the code is rather confusing. And, at
least to me, "scale" sounds an odd name there, especially as it's then
assigned to "max" local var. But if you and Thierry think this version
is good, I'll take it.

 Tomi



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