linux-kernel - Re: [PATCH] pwm_backlight: pass correct brightness to callback

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Message-ID: <4FFA6BCA.2040101@nvidia.com>
Date:	Mon, 9 Jul 2012 14:27:38 +0900
From:	Alex Courbot <acourbot@...dia.com>
To:	Thierry Reding <thierry.reding@...onic-design.de>
CC:	"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: pass correct brightness to callback

On 07/09/2012 02:10 PM, Thierry Reding wrote:
> I had to actually read this patch a number of times and then realized I
> was completely missing the context. Looking at the whole function makes
> it more obvious what you mean.
>
> However I think it'd be much clearer if we just passed the value of
> bl->props.brightness into the callbacks, that way we can avoid the
> additional variable.

This won't work I'm afraid, as brightness can be modified prior to being 
passed to the callback function:

	if (bl->props.power != FB_BLANK_UNBLANK)
		brightness = 0;

	if (bl->props.fb_blank != FB_BLANK_UNBLANK)
		brightness = 0;

	if (pb->notify)
		brightness = pb->notify(pb->dev, brightness);

Alex.
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