linux-kernel - Re: [PATCH] thinkpad_acpi: Add support for keyboard backlight

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Date:	Wed, 13 Jan 2016 20:07:36 +0100
From:	Pavel Machek <pavel@....cz>
To:	Pali Rohár <pali.rohar@...il.com>
Cc:	Henrique de Moraes Holschuh <hmh@....eng.br>,
	Darren Hart <dvhart@...radead.org>,
	ibm-acpi-devel@...ts.sourceforge.net,
	platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org,
	Fabio D'Urso <fabiodurso@...mail.it>
Subject: Re: [PATCH] thinkpad_acpi: Add support for keyboard backlight

On Wed 2016-01-13 09:54:55, Pali Rohár wrote:
> On Tuesday 12 January 2016 22:58:04 Pavel Machek wrote:
> > Hi!
> > 
> > On Mon 2016-01-11 21:03:01, Pali Rohár wrote:
> > > On Monday 11 January 2016 20:28:00 Henrique de Moraes Holschuh wrote
> > > > The two features are not the same (and are handled differently by the
> > > > firmware, for whatever reason), although they do serve the same
> > > > purpose. I don't think a thinkpad will ever have both features at
> > > > the same time, so I have no idea why they changed the firmware
> > > > interface.
> > > 
> > > Maybe we should decide if ::kbd_backlight LED suffix could be used also 
> > > for other LED devices and not only for those which are physically under 
> > > the keyboard.
> > 
> > Another problem is that N900 has _6_ backlight LEDs. Named
> > lp5523::kb1..6. ... Which does means desktop software will probably
> > not pick them up :-(. 
> > 
> > I guess we could have "/sys/class/kbd_light/brightness" that would
> > control all of them with one write.
> 
> Probably... But there is problem that lp5523 is not ordinary on/off
> light, it can be programmed to execute own "light" application.

Yeah, but that's not a problem, right. lp5523 can still set brightness
by hand.

> > Next question is.. apparently there are some keyboards that have
> > per-key RGB backlight... but maybe we can just call that "weird
> > enough" and ignore...
> 
> First we need to defines stable kernel ABI for keyboard backlight. And I
> suggest to use existing convention used by upower/console-kit and other
> userspace apps...

Hmm... I'm not sure that can be done. What were the masks used by
upower again? Will upower write to all 6 leds if we present them?

									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html