From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jani Nikula Subject: Re: i915 black screen introduced by ACPI changes Date: Mon, 11 Mar 2013 15:16:08 +0200 Message-ID: <87txoit6uf.fsf@intel.com> References: <20130219100849.72d2330b@jbarnes-desktop> <20130219125217.6b6f55ff@jbarnes-desktop> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mga02.intel.com (mga02.intel.com [134.134.136.20]) by gabe.freedesktop.org (Postfix) with ESMTP id 94BC8E5DE8 for ; Mon, 11 Mar 2013 06:15:32 -0700 (PDT) In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org Errors-To: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org To: Chris Li , Daniel Vetter Cc: len.brown@intel.com, feng.tang@intel.com, intel-gfx , robert.moore@intel.com, linux-kernel@vger.kernel.org, Linus Torvalds List-Id: intel-gfx@lists.freedesktop.org On Tue, 05 Mar 2013, Chris Li wrote: > On Mon, Mar 4, 2013 at 3:16 PM, Chris Li wrote: >>>> Two things to test: >>>> - Can you please check whether any of the backlight drivers in >>>> /sys/class/backlight does anything? You need to frob the brightness >>>> file. Please also list all the drivers you have. > > This is the kernel with the ACPI change causing the black screen. > > lrwxrwxrwx. 1 root root 0 Mar 4 15:20 acpi_video0 -> > ../../devices/pci0000:00/0000:00:01.0/0000:01:00.0/backlight/acpi_video0 > lrwxrwxrwx. 1 root root 0 Mar 4 15:20 acpi_video1 -> > ../../devices/pci0000:00/0000:00:02.0/backlight/acpi_video1 > lrwxrwxrwx. 1 root root 0 Mar 4 15:20 intel_backlight -> > ../../devices/pci0000:00/0000:00:02.0/drm/card0/card0-LVDS-1/intel_backlight > > Here is the interesting part. The brightness and max_brightness is all > set to 4648, > However, the actual brightness is 0. The bl_power is also 0. I think > you are on to some thing. Hi Chris - Interesting snippets from your dmesgs: 1) good [ 0.000000] Linux version 3.6.0-rc6+ (chrisl@ideapad.lan) (gcc version 4.7.2 20121109 (Red Hat 4.7.2-8) (GCC) ) #25 SMP Wed Feb 20 12:55:06 PST 2013 ... [ 5.341431] [drm:intel_panel_get_max_backlight], max backlight PWM = 4648 [ 5.341442] [drm:intel_panel_actually_set_backlight], set backlight PWM = 4648 [ 5.342572] [drm:intel_panel_get_max_backlight], max backlight PWM = 4648 [ 5.342578] [drm:intel_panel_actually_set_backlight], set backlight PWM = 4648 2) bad [ 0.000000] Linux version 3.8.0-rc7+ (chrisl@ideapad.lan) (gcc version 4.7.2 20121109 (Red Hat 4.7.2-8) (GCC) ) #23 SMP Tue Feb 19 19:24:57 PST 2013 ... [ 5.692853] [drm:asle_set_backlight], bclp = 0x800000ff [ 5.692865] [drm:intel_panel_get_max_backlight], max backlight PWM = 4648 [ 5.692870] [drm:intel_panel_actually_set_backlight], set backlight PWM = 4648 [ 5.693401] [drm:asle_set_backlight], bclp = 0x80000000 [ 5.693408] [drm:intel_panel_get_max_backlight], max backlight PWM = 4648 [ 5.693413] [drm:intel_panel_actually_set_backlight], set backlight PWM = 0 (We've added another debug print to asle_set_backlight.) For some reason we get two asle requests in a row. In the good kernel it's the same request twice, in the bad kernel the second requests is for 0 backlight. The register dumps seem to confirm this. Please try a recent kernel, with and without the the bisected bad commit commit a57f7f9175b8ccbc9df83ac13860488913115de4 Author: Bob Moore Date: Fri Aug 17 10:55:02 2012 +0800 ACPICA: Add Windows8/Server2012 string for _OSI method. reverted. Is the difference the same? Check reg dumps and dmesgs with drm.debug=0xe. Thanks, Jani.