From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jani Nikula Subject: Re: [Intel-gfx] i915 monitor hotplug on 4.1/4.4 PREEMPT Date: Thu, 20 Oct 2016 17:08:50 +0300 Message-ID: <87h987qfil.fsf@intel.com> References: <87r37bqk6d.fsf@intel.com> <20161020125708.GB8202@suiko.acc.umu.se> Mime-Version: 1.0 Content-Type: text/plain Cc: Nicolae Rosia , "linux-rt-users\@vger.kernel.org" , dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org To: David Weinehall Return-path: Received: from mga09.intel.com ([134.134.136.24]:54879 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756773AbcJTOIx (ORCPT ); Thu, 20 Oct 2016 10:08:53 -0400 In-Reply-To: <20161020125708.GB8202@suiko.acc.umu.se> Sender: linux-rt-users-owner@vger.kernel.org List-ID: On Thu, 20 Oct 2016, David Weinehall wrote: > On Thu, Oct 20, 2016 at 03:28:10PM +0300, Jani Nikula wrote: >> On Thu, 20 Oct 2016, Nicolae Rosia wrote: >> > Monitor hotplugging seems to be broken on latest 4.1/4.4 RT kernel with i915. >> > I have tested this on non-RT kernel and it works. > > The answer to your first question seems to be here :) *blush* >> > I get an udev event for unplugging, but there's no event generated for >> > plugging the monitor back in. >> >> Does it work on non-RT? Does it work on v4.8 or v4.9-rc1? > > The second one is relevant though. 4.1 is pre-historic, 4.4 is ancient. I think the honest answer here is that we do not have the resources to debug RT vs. non-RT issues all that much in general, and especially not for such old kernels. RT is not in our focus, and hotplug has proved to be hard enough on non-RT. Nothing to be proud of, but we have 500+ bugs open over at the freedesktop.org bugzilla, most for relatively recent non-RT kernels. Even if we fixed this upstream (and it would have to be fixed upstream to be backported) it's a huge problem that the feedback loop for RT kernels has such a long delay. If we break something for RT, it takes forever for us to find out. BR, Jani. -- Jani Nikula, Intel Open Source Technology Center