Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758744Ab3GaCHs (ORCPT ); Tue, 30 Jul 2013 22:07:48 -0400 Received: from mail-lb0-f169.google.com ([209.85.217.169]:61798 "EHLO mail-lb0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751560Ab3GaCHq (ORCPT ); Tue, 30 Jul 2013 22:07:46 -0400 MIME-Version: 1.0 In-Reply-To: <51F86A20.3060309@gmail.com> References: <1375125658-1223-1-git-send-email-felipe.contreras@gmail.com> <3453253.oZLO1ChPbL@vostro.rjw.lan> <37178266.QXgbv9rq0i@vostro.rjw.lan> <51F86A20.3060309@gmail.com> Date: Tue, 30 Jul 2013 21:07:44 -0500 Message-ID: Subject: Re: [REGRESSION/PATCH] acpi: blacklist win8 OSI for ASUS Zenbok Prime UX31A From: Felipe Contreras To: Aaron Lu Cc: "Rafael J. Wysocki" , linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, Len Brown , Linus Torvalds Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3124 Lines: 75 On Tue, Jul 30, 2013 at 8:36 PM, Aaron Lu wrote: > On 07/31/2013 08:11 AM, Felipe Contreras wrote: >> On Tue, Jul 30, 2013 at 6:13 PM, Rafael J. Wysocki wrote: >> >>>> If 0 turns the screen off with the intel driver, 0 should turn the >>>> screen off with the ACPI driver, having inconsistent behavior >>>> depending on which driver is used is a bug. >>> >>> The ACPI driver simply exposes and interface to interact with the AML methods >>> in the BIOS directly. >> >> No, the ACPI driver is exposing a backlight interface, which has a >> defined stable API. >> >> Documentation/ABI/stable/sysfs-class-backlight >> >> Yes, the interface doesn't define what should happen at 0, that is a >> bug in the interface definition. >> >> *How* it achieves that is an implementation detail. >> >>> Yes, this is a mistake and shouldn't be designed this way. >>> >>> However, incidentally, this makes backlight control work on your machine. >>> >>> Anyway, we need all backlight drivers to work consistently and don't tempt me >>> to rip the ACPI driver entirely from the kernel for what it's worth. >> >> Yes, they should work consistently, and go ahead, rip the ACPI driver, >> *then* you'll see many more people complaining about the Linux kernel >> breaking user-space, which should never happen. Mistakes happen, but >> if you do this willingly and knowingly, I think there would be >> repercussions for you. >> >>> Yes, that will break backlight on your system and *then* you can complain to >>> Linus if you wish. >> >> It is already broken in v3.11-rc3, in fact I just booted that to try >> it out and it booted with the screen completely black (fortunately I >> knew exactly what to type to change that). > > That is bad, can you please file a bug for that? I'll need to take a > look at your ACPI tables, thanks. File a bug where? >> Apparently this commit also needs to be reverted: efaa14c (ACPI / >> video: no automatic brightness changes by win8-compatible firmware). >> In this machine it makes the backlight work again (without >> acpi_osi="!Windows 2012"), but by doing so the ACPI driver also turns >> off the screen completely at level 0. Also, each time I change the > > So with rc3 and commit efaa14c reverted, when you set level 0 to ACPI > video's backlight interface, the screen will be off now? And this is not > the case in 3.10, right? No, setting level 0 turns it off if efaa14c is *not* reverted. In 3.10 0 doesn't turn it off. >> backlight level from X, the screen blinks as if going 100%, 0%, and >> then the desired level. > > Please attach acpidump output to the to be opened bugzilla page, thanks. I looked at the code in the DCDT, it appears to me that they store different levels depending on the OSI version, so I don't think the problem is in the ACPI driver. Yet, the issue remains there. -- Felipe Contreras -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/