linux-kernel - Re: [patch] added brightness feature to lcd class.

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Date:	Fri, 13 Nov 2009 12:13:54 +0900
From:	InKi Dae <daeinki@...il.com>
To:	Richard Purdie <rpurdie@...ux.intel.com>
Cc:	linux-fbdev-devel@...ts.sourceforge.net,
	linux-kernel@...r.kernel.org, Kyungmin Park <kmpark@...radead.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Pavel Machek <pavel@....cz>
Subject: Re: [patch] added brightness feature to lcd class.

Ok, I understood your answer.
Just it was my idea for AMOLED LCD Panel.
Both of them (AMOLED, TFT-LCD) do same thing in terms of brightness
control as you said.

Thank you, Richard.

Best Regards,
InKi Dae.

2009/11/11 Richard Purdie <rpurdie@...ux.intel.com>:
> On Wed, 2009-11-11 at 15:17 +0900, InKi Dae wrote:
>> 2009/11/10 Richard Purdie <rpurdie@...ux.intel.com>:
>> > So you've tried this, what was the problem? Perhaps post this driver
>> > code to illustrate your problem?
>>
>> all the cases worked fine.
>> it's not whether lcd driver has a problem or not.
>> I mean it's design issue of lcd class. AMOLED LCD Panel DOESN'T NEED
>> backlight device.
>> and I should have added brightness control feature to AMOLED LCD Panel
>> driver not using backlight class
>> because they have no BACKLIGHT DEVICE.
>>
>> in point of view AMOLED LCD Panel, brightness control is perfomed by
>> gamma setting, not backlight power controlling.
>
> The question is whether this gamma control does the same thing as what
> we've traditionally used the backlight brightness control for. As I
> understand it, the answer is yes and to userspace making it appear as a
> backlight brightness control makes sense.
>
> The userspace view of the world is key and the fact there is not a
> traditional physical backlight in the hardware isn't really an issue.
>
> Why would we want to create two userspace interfaces doing the same
> thing which would mean we just have to complicate userspace drivers?
> Symlinking just makes things confusing.
>
> Cheers,
>
> Richard
>
>
>
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