Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751907AbdCPKJV (ORCPT ); Thu, 16 Mar 2017 06:09:21 -0400 Received: from mail-yw0-f172.google.com ([209.85.161.172]:35597 "EHLO mail-yw0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751795AbdCPKJT (ORCPT ); Thu, 16 Mar 2017 06:09:19 -0400 MIME-Version: 1.0 In-Reply-To: <20170316095553.1586-1-michel@daenzer.net> References: <20170316095553.1586-1-michel@daenzer.net> From: Daniel Stone Date: Thu, 16 Mar 2017 10:09:17 +0000 Message-ID: Subject: Re: [PATCH] drm/fb-helper: Only reject FB changes if FB_MISC_USER_EVENT is set To: =?UTF-8?Q?Michel_D=C3=A4nzer?= Cc: dri-devel , Linux Kernel Mailing List Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by mail.home.local id v2GA9UZV004496 Content-Length: 1020 Lines: 27 Hi, On 16 March 2017 at 09:55, Michel Dänzer wrote: > Otherwise this can also prevent modesets e.g. for switching VTs. > > FB_MISC_USER_EVENT is set when the request originates from userspace, > which is what we're interested in here according to the DRM_DEBUG > output. > > Bugzilla: https://bugs.freedesktop.org/99841 > Fixes: 865afb11949e ("drm/fb-helper: reject any changes to the fbdev") > Signed-off-by: Michel Dänzer > --- > > I'm not entirely sure why the values can not match for a VT switch. If > anybody thinks this just papers over the real issue, please speak up. It happens for me in multi-head with different resolutions. A real compositor will set native resolutions with separate framebuffers, and then fbcon will try to set one buffer for both outputs. This works on the output with the larger resolution, but the one with the smaller resolution will fail due to [xy]res_virtual (IIRC) being different. I'll test this out later today. Cheers, Daniel