From mboxrd@z Thu Jan 1 00:00:00 1970 From: Felipe Contreras Subject: Re: [REGRESSION/PATCH] acpi: blacklist win8 OSI for ASUS Zenbok Prime UX31A Date: Wed, 31 Jul 2013 12:46:04 -0500 Message-ID: References: <1375125658-1223-1-git-send-email-felipe.contreras@gmail.com> <3453253.oZLO1ChPbL@vostro.rjw.lan> <37178266.QXgbv9rq0i@vostro.rjw.lan> <20130731051421.GA15766@srcf.ucam.org> <20130731140010.GA24560@srcf.ucam.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Return-path: In-Reply-To: <20130731140010.GA24560@srcf.ucam.org> Sender: linux-kernel-owner@vger.kernel.org To: Matthew Garrett Cc: "Rafael J. Wysocki" , Aaron Lu , linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, Len Brown , Linus Torvalds List-Id: linux-acpi@vger.kernel.org On Wed, Jul 31, 2013 at 9:00 AM, Matthew Garrett wrote: > On Wed, Jul 31, 2013 at 06:32:47AM -0500, Felipe Contreras wrote: >> On Wed, Jul 31, 2013 at 12:14 AM, Matthew Garrett wrote: >> > There's no mechanism for an OS to know whether or not a firmware >> > implementation will actually turn the backlight off at 0, so there's no >> > way the OS can define the lowest backlight state as anything other than >> > "May or may not turn the screen off". >> >> Yes there is; quirks. > > We aren't going to maintain a quirk list in order to support a guarantee > that was never made. "0" as a backlight level has potentially meant > "screen off" since the interface was first introduced. That doesn't change the fact that you were wrong, and there *is* actually a way. The fact that you don't want to go there doesn't mean it's not there. Here's another: device tree. There are ways to provide a consistent backlight interface to user-space. -- Felipe Contreras