From mboxrd@z Thu Jan 1 00:00:00 1970 From: Henrique de Moraes Holschuh Subject: Re: brightness control on thinkpad t61p Date: Tue, 8 Jan 2008 10:06:53 -0200 Message-ID: <20080108120653.GA23216@khazad-dum.debian.net> References: <20071223000057.739d5891.akpm@linux-foundation.org> <20071224073406.GA1018@srcf.ucam.org> <20071226141027.6d1a509f.akpm@linux-foundation.org> <20071226222321.GA32297@srcf.ucam.org> <20071227123358.GB25535@khazad-dum.debian.net> <20080107013623.GA6667@khazad-dum.debian.net> <20080107194833.GA22506@srcf.ucam.org> <20080108003246.GA15587@khazad-dum.debian.net> <20080108004559.GA27177@srcf.ucam.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from out5.smtp.messagingengine.com ([66.111.4.29]:59036 "EHLO out5.smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750715AbYAHMG6 (ORCPT ); Tue, 8 Jan 2008 07:06:58 -0500 Content-Disposition: inline In-Reply-To: <20080108004559.GA27177@srcf.ucam.org> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Matthew Garrett Cc: Andrew Morton , linux-acpi@vger.kernel.org, "Rafael J. Wysocki" On Tue, 08 Jan 2008, Matthew Garrett wrote: > On Mon, Jan 07, 2008 at 10:32:46PM -0200, Henrique de Moraes Holschuh wrote: > > > Should we? Why? We lose information doing that. Instead of a nice linear > > 0-100% brightness scale, you are now back to an 8 or 16-level non-linear > > brightness scale. > > The spec makes no guarantees about what that 0-100 range means - it may > be brightness, power consumption or bonghits. It's really not guaranteed > to be meaningful, and the backlight class doesn't provide that guarantee > either. True. But it is still a step backwards for firmware that do better. And, frankly, the backlight class is so spartan, I don't consider missing features in it anything but a "time to fix it" issue. It is just like the LED class, it is too spartan to actually do all we need it to in some cases. Is there a *real* technical reason why we can't just round to the nearest? That will work well with any firmware, and it will not remove functionality from any box, while at the same time plugging the current issues nicely. -- "One disk to rule them all, One disk to find them. One disk to bring them all and in the darkness grind them. In the Land of Redmond where the shadows lie." -- The Silicon Valley Tarot Henrique Holschuh