From mboxrd@z Thu Jan 1 00:00:00 1970 From: Seth Forshee Subject: Re: [PATCH v2] platform/x86: Add driver for Apple gmux device Date: Mon, 12 Mar 2012 10:18:52 -0500 Message-ID: <20120312151852.GB12322@ubuntu-macmini> References: <1329424465-1211-1-git-send-email-seth.forshee@canonical.com> <1329921457-26887-1-git-send-email-seth.forshee@canonical.com> <20120312142126.GA11969@srcf.ucam.org> <20120312145701.GA12322@ubuntu-macmini> <20120312150717.GA13211@srcf.ucam.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from youngberry.canonical.com ([91.189.89.112]:38093 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755789Ab2CLPSz (ORCPT ); Mon, 12 Mar 2012 11:18:55 -0400 Content-Disposition: inline In-Reply-To: <20120312150717.GA13211@srcf.ucam.org> Sender: platform-driver-x86-owner@vger.kernel.org List-ID: To: Matthew Garrett Cc: platform-driver-x86@vger.kernel.org, linux-kernel@vger.kernel.org On Mon, Mar 12, 2012 at 03:07:17PM +0000, Matthew Garrett wrote: > > We also have the problem of gmux_backlight versus acpi_video. On most > > machines with a gmux the acpi_video backlight interface is present but > > just doesn't work. This problem isn't just limited to Apples. I'm of the > > opinion that we need a more generalized solution for arbitrating between > > the backlight interfaces present on a given machine, but I haven't had a > > chance to really think about what that would look like. > > The ACPI code appears to be trapping into system management mode, so > figuring out what it's meant to do is going to be awkward. I think > having a hook in the ACPI video driver to deregister it in cases where > we know it doesn't work is legitimate, but since it presumably works > under Windows it'd be nice to figure out what's broken about it. Why do you presume it works under Windows? Boot camp installs a pile of drivers for Windows, one of those could be a driver for the backlight. I don't know either way. But it's pretty clear that MacOS is using the gmux for the backlight when it is present from the reverse engineering work done by others. Seth