From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Garrett Subject: Re: [PATCH v3] ACPI / video: Add systems that should favor native backlight interface Date: Tue, 21 Jan 2014 03:17:51 +0000 Message-ID: <1390274270.5320.2.camel@x230> References: <1390053249-18919-1-git-send-email-i.gnatenko.brain@gmail.com> <52DCDA75.2000108@intel.com> <1390224857.10605.0.camel@x230> <52DDDA64.90407@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <52DDDA64.90407@intel.com> Content-Language: en-US Content-ID: <9712A04C2E3DEE42BE8F45FFB40B87A1@namprd05.prod.outlook.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: intel-gfx-bounces@lists.freedesktop.org Errors-To: intel-gfx-bounces@lists.freedesktop.org To: "aaron.lu@intel.com" Cc: "james@albanarts.com" , "bitbucket@online.de" , "felipe.contreras@gmail.com" , "dri-devel@lists.freedesktop.org" , "platform-driver-x86@vger.kernel.org" , "hmh@hmh.eng.br" , "kvalo@adurom.com" , "corsac@debian.org" , "linux-acpi@vger.kernel.org" , "joeyli.kernel@gmail.com" , "ben@bjencks.net" , "jrg.otte@gmail.com" , "intel-gfx@lists.freedesktop.org" , "Martin@lichtvoll.de" , "thirdwiggin@gmail.com" , "bugs@ttyhoney.com" , "jplatte@naasa.net" , "seth.forshee@canonical.com" List-Id: intel-gfx@lists.freedesktop.org On Tue, 2014-01-21 at 10:24 +0800, Aaron Lu wrote: > On 01/20/2014 09:34 PM, Matthew Garrett wrote: > > On Mon, 2014-01-20 at 16:12 +0800, Aaron Lu wrote: > > > >> 1 remove the win8 OSI check, I've seen win7 laptops that also needs to > >> have only the GPU interface left and checking win8 doesn't make much > >> sense now; > > > > Are we sure that those aren't simply some other bug? > > Well, the firmware on that laptop makes use of EC to do backlight > control and the fact that the firmware interface doesn't work while the > GPU's work seems to indicate that the backlight control circuit is not > routed to EC. I think this is the same case as Win8 laptops. We know that Windows 8 graphics drivers don't use the ACPI interface, and that systems change their behaviour as a result, in some cases with absolutely no way for the ACPI interface could possibly work. I haven't seen any cases where that's obviously true for any non-Windows 8 systems. EC interfaces that don't work are often due to Linux leaving the hardware in a state other than the one expected by the firmware. We shouldn't assume that it's the same issue until we've investigated further. -- Matthew Garrett