From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756047AbYA0GBp (ORCPT ); Sun, 27 Jan 2008 01:01:45 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752189AbYA0GBN (ORCPT ); Sun, 27 Jan 2008 01:01:13 -0500 Received: from smtp2.linux-foundation.org ([207.189.120.14]:34247 "EHLO smtp2.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751006AbYA0GBL (ORCPT ); Sun, 27 Jan 2008 01:01:11 -0500 Date: Sat, 26 Jan 2008 22:00:45 -0800 From: Andrew Morton To: Len Brown Cc: mjg59@srcf.ucam.org, linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org Subject: Re: [PATCH] Rationalise ACPI backlight implementation Message-Id: <20080126220045.b93db7c9.akpm@linux-foundation.org> In-Reply-To: <200801241644.49114.lenb@kernel.org> References: <20071226020325.GA21099@srcf.ucam.org> <200801241644.49114.lenb@kernel.org> X-Mailer: Sylpheed version 2.2.4 (GTK+ 2.8.19; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On Thu, 24 Jan 2008 16:44:48 -0500 Len Brown wrote: > On Tuesday 25 December 2007 21:03, Matthew Garrett wrote: > > The sysfs backlight class provides no mechanism for querying the > > acceptable brightness for a backlight. The ACPI spec states that values > > are only valid if they are reported as available by the firmware. Since > > we can't provide that information to userspace, instead collapse the > > range to the number of actual values that can be set. > > > > Signed-off-by: Matthew Garrett > > I wish we did this in the first place. > But doing it now is an API change -- since > with the old way 100 always meant 100% brightness, yes? > > so my concern is that if we change what "10" means, somebody like akpm > with an existing script gets grumpy. It takes more than that to make me grumpy. I've been very grumpy lately. - Create a new /sys node with a new name which has the new semantics. - Deprecate the old /sys entry by emitting an angry printk when someone uses it. - Wait 12 months - Kill the old one.