From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932371AbcGHOuU (ORCPT ); Fri, 8 Jul 2016 10:50:20 -0400 Received: from bedivere.hansenpartnership.com ([66.63.167.143]:53476 "EHLO bedivere.hansenpartnership.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755165AbcGHOsi (ORCPT ); Fri, 8 Jul 2016 10:48:38 -0400 Message-ID: <1467989309.2245.2.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: "Syrjala, Ville" , intel-gfx , linux-kernel , dri-devel , Rodrigo Vivi Date: Fri, 08 Jul 2016 07:48:29 -0700 In-Reply-To: <20160708101934.GQ4329@intel.com> References: <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> <20160707161425.GO4329@intel.com> <1467910504.2322.9.camel@HansenPartnership.com> <1467919176.2322.38.camel@HansenPartnership.com> <20160708101934.GQ4329@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 Fri, 2016-07-08 at 13:19 +0300, Ville Syrjälä wrote: > On Thu, Jul 07, 2016 at 12:19:36PM -0700, James Bottomley wrote: > > On Thu, 2016-07-07 at 09:55 -0700, James Bottomley wrote: > > > On Thu, 2016-07-07 at 19:14 +0300, Ville Syrjälä wrote: > > > > On Tue, Jun 21, 2016 at 06:44:34PM +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. > > > > > > > > I did a quick once over of out DDI vswing stuff and didn't find > > > > anything too serious. There were some buglets in the iboost > > > > handling, > > > > but I'm not very hopeful that fixing those would help with your > > > > machine. > > > > > > > > Here's a branch anyway in case you want to give it a go: > > > > git://github.com/vsyrjala/linux.git ddi_iboost_fixes > > > > > > > > Actually, I think the only patch in there that might make a > > > > difference is 15d887855180 ("drm/i915: Fix iboost setting for > > > > DDI > > > > with 4 lanes on SKL") > > > > > > Running with it now (the entire branch). So far it looks OK, but > > > I'll give it a couple of days to see if anything manifests before > > > declaring victory. > > > > Bad news, I'm afraid: after a couple of hours of run time, there is > > now > > noticeable flicker on the display, so although the iboost fixes may > > have lessened it, it's still present. > > Oh well, I suspected as much. Which BIOS version did you have > exactly? As mentioned upthread, now 1.4.3 since skylake microcode was potentially implicated in the problem: http://mid.gmane.org/1466179729.2271.33.camel@HansenPartnership.com > If I'm reading the Dell website correctly there's a new one (1.4.4) > released on Jun 30, which is after you reported the issue. Might be > I'm reading the wrong thing though. Can you double check this? New bios doesn't change the microcode: [ 2.390172] microcode: CPU0 sig=0x406e3, pf=0x80, revision=0x8a And the flicker is still present. James