From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752063AbcFUPrt (ORCPT ); Tue, 21 Jun 2016 11:47:49 -0400 Received: from mga03.intel.com ([134.134.136.65]:8408 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751437AbcFUPrp (ORCPT ); Tue, 21 Jun 2016 11:47:45 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.26,504,1459839600"; d="scan'208";a="980474937" Date: Tue, 21 Jun 2016 18:44:34 +0300 From: Ville =?iso-8859-1?Q?Syrj=E4l=E4?= To: James Bottomley Cc: Jani Nikula , Daniel Vetter , intel-gfx , "Syrjala, Ville" , linux-kernel , dri-devel , Rodrigo Vivi Subject: Re: [Intel-gfx] Bad flicker on skylake HQD due to code in the 4.7 merge window Message-ID: <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> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1466517195.2291.2.camel@HansenPartnership.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. -- Ville Syrjälä Intel OTC