From mboxrd@z Thu Jan 1 00:00:00 1970 From: Richard Purdie Subject: Re: [PATCH 1/3] backlight: Allow drivers to update the core, and generate events on changes Date: Wed, 15 Jul 2009 10:11:29 +0100 Message-ID: <1247649089.20241.5.camel@dax.rpnet.com> References: <1247517685-7719-1-git-send-email-mjg@redhat.com> <1247574573.23871.8.camel@dax.rpnet.com> <1247644518.26272.88.camel@rzhang-dt> <1247646153.6248.3.camel@dax.rpnet.com> <1247647105.26272.99.camel@rzhang-dt> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: Received: from dan.rpsys.net ([93.97.175.187]:53551 "EHLO dan.rpsys.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753429AbZGOJPP (ORCPT ); Wed, 15 Jul 2009 05:15:15 -0400 In-Reply-To: <1247647105.26272.99.camel@rzhang-dt> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Zhang Rui Cc: Matthew Garrett , "linux-kernel@vger.kernel.org" , "linux-acpi@vger.kernel.org" , "lenb@kernel.org" , "corentincj@iksaif.net" On Wed, 2009-07-15 at 16:38 +0800, Zhang Rui wrote: > On Wed, 2009-07-15 at 16:22 +0800, Richard Purdie wrote: > > We don't have one that I'm aware of. > > > > The first question is what information and configuration options are we > > likely to have with ALS sensors? If its just a light level reading, the > > input subsystem is ideally suited for sharing that. Is there > > configuration we need to expose? > > > For an ACPI ALS device, only these two are mandatory > 1. the current ambient light illuminance. > 2. A list of luminance mappings, including the "display luminance > adjustment" and "ambient light illuminance", which can be used by OS to > determine the ambient light policy. So there are basically two values we're ever interested in at a given point in time. The current ambient light reading and the corresponding display luminance adjustment. Both of those could just be exposed as an input device really? > IMO, the ALS driver should just export these info to user space, and we > can do the display backlight adjustment in user space, > via /sys/class/backlight. Agreed, userspace should be where policy is decided. Having a standalone module which connected the two together with a "default" policy might be acceptable too though? If userspace then wants to handle things it just makes sure the module is not loaded. Cheers, Richard -- Richard Purdie Intel Open Source Technology Centre