Re: Advice on backlight support

From: Paul Sokolovsky
Date: Wed Feb 21 2007 - 11:14:47 EST

Hello Rodolfo,

Wednesday, February 21, 2007, 6:02:13 PM, you wrote:

> Hello,

> I'd like to add backlight support for input devices since my custom
> board has a backlighted mini keyboard.

There's already generic indicator API, currently mostly known as
"[new] LED [classdev] API", even though it is already used for things
like buzzers, vibrators, etc. Why wouldn't it be suitable for your

LCD and LCD backlight are special cases, as they actually should
track state of (abstract) FB device, and keeping their states in sync
is pretty important for trivial PM and info accessibility, so worth
doing on kernel level.

As for things like "light up keyboard if key was pressed, then light
down after timeout", or "light up backlight LCD on touchscreen touch,
light down on timeout", that can be pretty well done in userspace, no?

> It could be acceptable to move the code from drivers/video/backlight/
> to drivers/backlight/ renaming the "Backlight & LCD" name into
> "Backlight" and adding two new entries "LCD" and, maybe, "Input" (or
> something like that?).

Yes, the fact that lcd.c (LCD power control) lives under backlight
dir, is a bit confusing. But they still has close relation to FB,
after all.

> Thanks in advance,

> Rodolfo

Best regards,
Paul mailto:pmiscml@xxxxxxxxx

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