From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755084AbZHOQUw (ORCPT ); Sat, 15 Aug 2009 12:20:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754279AbZHOQUw (ORCPT ); Sat, 15 Aug 2009 12:20:52 -0400 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:60847 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754122AbZHOQUv (ORCPT ); Sat, 15 Aug 2009 12:20:51 -0400 Date: Fri, 14 Aug 2009 18:32:33 +0200 From: Pavel Machek To: Matthew Garrett Cc: "Tippett, Matthew" , "Langsdorf, Mark" , lenb@kernel.org, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, "Li, Samuel" Subject: Re: [PATCH][ACPI] AC/DC notifier Message-ID: <20090814163233.GC1626@ucw.cz> References: <20090812005532.GA31003@srcf.ucam.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090812005532.GA31003@srcf.ucam.org> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 2009-08-12 01:55:32, Matthew Garrett wrote: > On Tue, Aug 11, 2009 at 08:51:49PM -0400, Tippett, Matthew wrote: > > > From a graphics perspective (your area of expertise), this will allow KMS > > drivers to do some more intelligent actions based on the ac/dc state. > > Some examples of this could be improving the power consumption of the > > graphics hardware through adapting clock memory/engine settings for > > reduced power consumption, reducing refresh rate of the display to reduce > > scanout memory access, adjusting backlight brightness, etc. > > Right. As you say, my concern is that most of this should belong in > userspace. Where we risk hardware damage there's an obvious argument for > doing this in kernel, but we should ensure that that's limited to > whatever coarse-grain handling is absolutely required rather than doing > things like touching display brightness. Yep... Some may want to save power even when AC is online -- like when running on UPS. Some may want max performmance even on battery. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html