Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753307Ab3FNR3z (ORCPT ); Fri, 14 Jun 2013 13:29:55 -0400 Received: from mail-bn1lp0152.outbound.protection.outlook.com ([207.46.163.152]:47647 "EHLO na01-bn1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752615Ab3FNR3w (ORCPT ); Fri, 14 Jun 2013 13:29:52 -0400 From: Matthew Garrett To: Aaron Lu CC: "linux-acpi@vger.kernel.org" , Seth Forshee , "Lee, Chun-Yi" , "daniel.vetter@ffwll.ch" , "intel-gfx@lists.freedesktop.org" , "dri-devel@lists.freedesktop.org" , "linux-kernel@vger.kernel.org" , Len Brown , "Rafael J. Wysocki" , Zhang Rui , Aaron Lu , Alex Deucher Subject: Re: [PATCH 3/3] i915: Don't provide ACPI backlight interface if firmware expects Windows 8 Thread-Topic: [PATCH 3/3] i915: Don't provide ACPI backlight interface if firmware expects Windows 8 Thread-Index: AQHOZWVb86pe7osyu0+xw9CXu6ntE5k0yzOAgACziwA= Date: Fri, 14 Jun 2013 17:29:48 +0000 Message-ID: <1371230988.2490.2.camel@x230> References: <1370818899-8595-1-git-send-email-matthew.garrett@nebula.com> <1370818899-8595-4-git-send-email-matthew.garrett@nebula.com> <51BABC6F.3050201@intel.com> In-Reply-To: <51BABC6F.3050201@intel.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.255.84.4] x-forefront-antispam-report: SFV:SKI;SFS:;DIR:OUT;SFP:;SCL:-1;SRVR:BY2PR05MB223;H:BY2PR05MB222.namprd05.prod.outlook.com;LANG:en; Content-Type: text/plain; charset="utf-8" Content-ID: <89367251F921144BA1652F68756238DC@namprd05.prod.outlook.com> MIME-Version: 1.0 X-OriginatorOrg: nebula.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by mail.home.local id r5EHU1lY006778 Content-Length: 1512 Lines: 31 On Fri, 2013-06-14 at 14:47 +0800, Aaron Lu wrote: > What about a priority based solution? We can introduce a new field named > priority to backlight_device and instead of calling another module's > function like the unregister one here(which cause unnecessary module > dependency), we only need to boost priority for its own interface. This > field will be exported to sysfs, so user can change it during runtime > too. And we can also introduce a new kernel command line as > backlight.force_interface=raw/firmware/platform, to overcome the limited > functionality provided by acpi_backlight=video/vendor, which does not > involve GPU's interface. How would that work with existing userspace? > And we can place the quirk code in backlight layer instead of individual > backlight functionality provider module. Suppose we have a backlight > manager there, for all win8 systems, we can boost the raw type's > priority on its registration, so no need to add code in > intel/amd/etc./'s GPU driver code. But we'd need to add code to every piece of userspace that currently uses the backlight, right? > With priority based solution, all backlight control interfaces stay, > the priority field is an indication given by kernel to user space. We shouldn't export interfaces if we don't expect them to work. -- Matthew Garrett | mjg59@srcf.ucam.org ????{.n?+???????+%?????ݶ??w??{.n?+????{??G?????{ay?ʇڙ?,j??f???h?????????z_??(?階?ݢj"???m??????G????????????&???~???iO???z??v?^?m???? ????????I?