From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756944AbcAUDtJ (ORCPT ); Wed, 20 Jan 2016 22:49:09 -0500 Received: from darkcity.gna.ch ([195.226.6.51]:51382 "EHLO mail.gna.ch" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752036AbcAUDtG (ORCPT ); Wed, 20 Jan 2016 22:49:06 -0500 X-Greylist: delayed 341 seconds by postgrey-1.27 at vger.kernel.org; Wed, 20 Jan 2016 22:49:06 EST Subject: Re: linux-4.4 bisected: kwin5 stuck on kde5 loading screen with radeon To: Mario Kleiner , Vlastimil Babka , =?UTF-8?B?VmlsbGUgU3lyasOkbMOk?= References: <5698CB20.9050602@suse.cz> <20160115122629.GC23290@intel.com> <5699C5E5.90702@gmail.com> <569CC357.8030302@suse.cz> <569FEEDE.4060409@gmail.com> Cc: Daniel Vetter , LKML , dri-devel@lists.freedesktop.org, mgraesslin@kde.org, kwin@kde.org, Alex Deucher , =?UTF-8?Q?Christian_K=c3=b6nig?= From: =?UTF-8?Q?Michel_D=c3=a4nzer?= X-Enigmail-Draft-Status: N1110 Message-ID: <56A053CE.7000500@daenzer.net> Date: Thu, 21 Jan 2016 12:43:10 +0900 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Icedove/38.5.0 MIME-Version: 1.0 In-Reply-To: <569FEEDE.4060409@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 21.01.2016 05:32, Mario Kleiner wrote: > > So the problem is that AMDs hardware frame counters reset to > zero during a modeset. The old DRM code dealt with drivers doing that by > keeping vblank irqs enabled during modesets and incrementing vblank > count by one during each vblank irq, i think that's what > drm_vblank_pre_modeset() and drm_vblank_post_modeset() were meant for. Right, looks like there's been a regression breaking this. I suspect the problem is that vblank->last isn't getting updated from drm_vblank_post_modeset. Not sure which change broke that though, or how to fix it. Ville? BTW, I'm seeing a similar issue with drm_vblank_on/off as well, which exposed the bug fixed by 209e4dbc ("drm/vblank: Use u32 consistently for vblank counters"). I've been meaning to track that down since then; one of these days hopefully, but if anybody has any ideas offhand... -- Earthling Michel Dänzer | http://www.amd.com Libre software enthusiast | Mesa and X developer