From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932075AbcGGTTo (ORCPT ); Thu, 7 Jul 2016 15:19:44 -0400 Received: from bedivere.hansenpartnership.com ([66.63.167.143]:48064 "EHLO bedivere.hansenpartnership.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751233AbcGGTTi (ORCPT ); Thu, 7 Jul 2016 15:19:38 -0400 Message-ID: <1467919176.2322.38.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: Thu, 07 Jul 2016 12:19:36 -0700 In-Reply-To: <1467910504.2322.9.camel@HansenPartnership.com> References: <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> <20160707161425.GO4329@intel.com> <1467910504.2322.9.camel@HansenPartnership.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 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. James