From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hans de Goede Subject: Re: Can't even enter X after kernel 4.12 Date: Tue, 5 Dec 2017 20:09:25 +0100 Message-ID: <7634b10f-cc73-4e82-1bef-b0ba837e6ccb@redhat.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail-wr0-f173.google.com ([209.85.128.173]:44325 "EHLO mail-wr0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752585AbdLETJ2 (ORCPT ); Tue, 5 Dec 2017 14:09:28 -0500 Received: by mail-wr0-f173.google.com with SMTP id l22so1437773wrc.11 for ; Tue, 05 Dec 2017 11:09:28 -0800 (PST) In-Reply-To: Content-Language: en-US Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Chris Chiu Cc: linux-acpi@vger.kernel.org, Linux Upstreaming Team Hi, On 05-12-17 16:42, Chris Chiu wrote: > On Tue, Dec 5, 2017 at 6:40 AM, Hans de Goede wrote: >> Hi Chris, >> >> On 30-11-17 07:27, Chris Chiu wrote: >>> >>> Hi, >>> I have a Intel cherry trail machine Haier HR101CW (CPU: x5-Z8350) >>> which used to work fine in kernel 4.11, fails to enter X after I >>> upgrade to kernel version later than 4.12. Even the latest 4.15, it >>> can't even enter X now. There's no panic, oops and even no obvious >>> error log. The panel backlight seems to be off but keyboard still >>> responds. >>> >>> Then I tried to do bisect, it tells me the commit >>> [b7ecf663c75eed1e764f57281f9508c49c18516e] ACPI / bus: Introduce a >>> list of ids for "always present" devices is the one which causes this. >>> After I revert this commit, the display back to normal. >>> >>> Maybe the DSDT file would help for your reference. >>> https://gist.github.com/mschiu77/e84687cc928ac644117baf05aef47f16 >> >> >> Hmm, Daniel Drake from Endless send me a Vios LTH17 machine which >> has similar symptoms. If this is indeed the same issue then adding: >> i915.fastboot=1 to the kernel commandline should fix this. >> >> This is going to be the default for newer kernels soon-ish (4.16 >> I think), so we can use this as a workaround for now. >> >> As for the commit you bisected this to, can you try just commenting >> out the: "80862288" entry in always_present_ids in >> drivers/acpi/x86/utils.c ? I think that is triggering the problem. >> >> Without that entry we don't get backlight control, so if you >> comment it you will likely not be able to control brightness, >> so i915.fastboot=1 is a better fix, but it would be good to know >> if commenting out just that entry fixes things (and breaks >> brightness control). >> >> Without i915.fastboot=1 the i915 driver quickly turns the >> backlight off and on again at boot, which I guess is confusing >> the LCD panel... >> >> Regards, >> >> Hans >> > > Hmm...the i915.fastboot=1 seems not work on my Haier machine here. > However, comment out the: "80862288" entry in always_present_ids in > drivers/acpi/x86/utils.c do work. Do you need anything on this special > machine? On the VIOS LTH17 I just need i915.fastboot=1 and then things work (with a 4.14 kernel) the 80862288 entry in that table makes Linux bind to the pwm controller in the Z8350, which is usually used for brightness control. Do you get a brightness slider in gnome3 with the 80862288 entry commented out? And does it work ? Regards, Hans