Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753170AbdFRVba (ORCPT ); Sun, 18 Jun 2017 17:31:30 -0400 Received: from emh07.mail.saunalahti.fi ([62.142.5.117]:60552 "EHLO emh07.mail.saunalahti.fi" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753114AbdFRVb2 (ORCPT ); Sun, 18 Jun 2017 17:31:28 -0400 Date: Mon, 19 Jun 2017 00:31:24 +0300 From: Aaro Koskinen To: Tomi Valkeinen Cc: Peter Ujfalusi , Tony Lindgren , linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org, dri-devel@lists.freedesktop.org Subject: Re: [BISECTED, REGRESSION] v4.12-rc: omapdrm fails to probe on Nokia N900 Message-ID: <20170618213124.ilacwpkh34rusliz@darkstar.musicnaut.iki.fi> References: <20170614221133.k7gmbzzjsbmbjgbc@darkstar.musicnaut.iki.fi> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1749 Lines: 43 Hi, On Thu, Jun 15, 2017 at 09:51:06AM +0300, Tomi Valkeinen wrote: > On 15/06/17 01:11, Aaro Koskinen wrote: > > When booting v4.12-rc5 on Nokia N900, omapdrm fails to probe and there > > is no display. > > Are you sure it doesn't probe? It fails the omapdss_stack_is_ready() > check? If that's the case then this is easier to debug. Yes I think so, I added debug prints to omap_connect_dssdevs() and pdev_probe(), and it's omapdss_stack_is_ready() that is failing. > > Bisected to: > > > > a09d2bc1503508c17ef3a71c6b1905e3660f3029 is the first bad commit > > commit a09d2bc1503508c17ef3a71c6b1905e3660f3029 > > Author: Peter Ujfalusi > > Date: Tue May 3 22:08:01 2016 +0300 > > > > drm/omap: Use omapdss_stack_is_ready() to check that the display stack is up > > > > Instead of 'guessing' based on aliases of the status of the DSS drivers, > > use the new interface to check that all needed drivers are loaded. > > In this way we can be sure that all needed drivers are loaded so it is > > safe to continue the probing of omapdrm. > > This method will allow the omapdrm to be probed 'headless', without > > outputs. > > > > Signed-off-by: Peter Ujfalusi > > Signed-off-by: Tomi Valkeinen > > > > Reverting the commit seems to fix the issue. > > This is probably "fixed" by adding the display aliases into the n900 dts > file. The aliases should not really be required, although they are > recommended. Without the aliases the order of the displays is random, > and n900 could end up using tv-out as the first display. But even then, > the displays should still work. I'm using up-to-date DTS from the kernel tree. A.