Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932391AbaBUAbq (ORCPT ); Thu, 20 Feb 2014 19:31:46 -0500 Received: from mail-ob0-f181.google.com ([209.85.214.181]:61169 "EHLO mail-ob0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932360AbaBUAbm (ORCPT ); Thu, 20 Feb 2014 19:31:42 -0500 MIME-Version: 1.0 In-Reply-To: References: Date: Thu, 20 Feb 2014 19:31:41 -0500 X-Google-Sender-Auth: hEzlJNQ39BsUDmoG0-vM_EtSLuM Message-ID: Subject: Re: 3.13 i915 brightness settings broken when going from docked -> undocked From: Josh Boyer To: Jesse Barnes , Daniel Vetter , Jani Nikula Cc: David Airlie , intel-gfx@lists.freedesktop.org, DRI mailing list , "Linux-Kernel@Vger. Kernel. Org" Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Feb 19, 2014 at 9:20 PM, Josh Boyer wrote: > Hi All, > > We've had a rather weird report[1] of the brightness adjustments being > broken in a specific case with Thinkpad x220 hardware (SandyBridge > based). If you boot the machine with it in a dock and then undock, > the brightness adjustments do not work. That is with either the FN > keys or the GNOME brightness slider. > > I can see that the value of > /sys/class/backlight/acpi_video0/brightness increases/decreases but > /sys/class/backlight/intel_backlight/brightness doesn't reflect any > changes. With 3.12 this works, and oddly with 3.14-rc1 it works > (specifically, it starts working around v3.13-10231-g53d8ab2 which is > right after the first DRM merge for 3.14). With 3.13, if I undock and > echo a higher value in the intel_backlight_brightness sysfs entry, the > brightness will actually increase so it can be done manually, but it > does not work as you'd expect. > > I'm in the middle of trying to do a reverse bisect for which patch > fixes it in the 3.14-rcX series, but that's taking a while. I thought > I'd email and see if anyone already knows about this situation, what > patch in 3.13 broke this, and which one then fixed it again. Thus far > all I've gathered is that backlight handling is confusing. The reverse bisect between 3.13 and 3.14-rc1 didn't prove fruitful, either because I messed it up or there's a combination of things that fix the issue. So instead I did a regular git bisect between 3.12 and 3.13 to see which commit _broke_ things and caused the above behavior. That landed me at: Author: Jesse Barnes Date: Thu Oct 31 18:55:49 2013 +0200 drm/i915: make backlight functions take a connector I have no idea if that makes sense or not, but it's at least something that seems to be in a relevant area of code. Does anyone involved in that know why it would cause the above symptoms on 3.13, and which commit(s) fix it in 3.14-rc1? josh -- 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/