From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751740AbcFUVAz (ORCPT ); Tue, 21 Jun 2016 17:00:55 -0400 Received: from bedivere.hansenpartnership.com ([66.63.167.143]:42464 "EHLO bedivere.hansenpartnership.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751270AbcFUVAx (ORCPT ); Tue, 21 Jun 2016 17:00:53 -0400 Message-ID: <1466542819.2441.5.camel@HansenPartnership.com> Subject: Re: [Intel-gfx] Bad flicker on skylake HQD due to code in the 4.7 merge window From: James Bottomley To: Ville =?ISO-8859-1?Q?Syrj=E4l=E4?= Cc: Jani Nikula , Daniel Vetter , intel-gfx , "Syrjala, Ville" , linux-kernel , dri-devel , Rodrigo Vivi Date: Tue, 21 Jun 2016 17:00:19 -0400 In-Reply-To: <20160621154434.GY4329@intel.com> References: <1466111747.2311.1.camel@HansenPartnership.com> <1466112547.2311.3.camel@HansenPartnership.com> <1466116932.2257.4.camel@HansenPartnership.com> <20160617072826.GI23520@phenom.ffwll.local> <87vb18uef2.fsf@intel.com> <1466204815.2199.2.camel@HansenPartnership.com> <1466373202.2280.3.camel@HansenPartnership.com> <8737o89ti7.fsf@intel.com> <1466517195.2291.2.camel@HansenPartnership.com> <20160621154434.GY4329@intel.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.16.5 Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2016-06-21 at 18:44 +0300, Ville Syrjälä wrote: > On Tue, Jun 21, 2016 at 09:53:15AM -0400, James Bottomley wrote: > > On Mon, 2016-06-20 at 11:03 +0300, Jani Nikula wrote: > > > Cc: Ville > > > > > > On Mon, 20 Jun 2016, James Bottomley < > > > James.Bottomley@HansenPartnership.com> wrote: > > > > OK, my candidate bad commit is this one: > > > > > > > > commit a05628195a0d9f3173dd9aa76f482aef692e46ee > > > > Author: Ville Syrjälä > > > > Date: Mon Apr 11 10:23:51 2016 +0300 > > > > > > > > drm/i915: Get panel_type from OpRegion panel details > > > > > > > > After being more careful about waiting to identify flicker, > > > > this one seems to be the one the bisect finds. I'm now running > > > > v4.7-rc3 with this one reverted and am currently seeing no > > > > flicker problems. It is, however, early days because the > > > > flicker can hide for long periods, so I 'll wait until Monday > > > > evening and a few reboots before declaring victory. > > > > > > If that turns out to be the bad commit, it doesn't really > > > surprise me, and that in itself is depressing. > > > > As far as I can tell, after running for a day with this reverted, > > this is the problem. The flicker hasn't appeared with it reverted. > > It's pretty noticeable with this commit included. > > Hmm. The only difference I can see is low vs. normal vswing. Panel 0 > has low, panel 2 has normal. So either the VBT or opregion is telling > utter lies, or there's some other bug in our low vswing support. > > To confirm it's really a vswing issue, you should be able to run with > i915.edp_vswing=2 without flickers on the broken kernel. Preliminary boot indicates no flicker with the bad commit included and this option, but I'll have to run for quite a bit longer to verify, since it can sometimes be elusive. James