From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtprelay.restena.lu ([158.64.1.62]:45518 "EHLO smtprelay.restena.lu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751236AbbE0GCY (ORCPT ); Wed, 27 May 2015 02:02:24 -0400 Date: Wed, 27 May 2015 07:53:29 +0200 From: Bruno =?UTF-8?B?UHLDqW1vbnQ=?= To: Michael Marineau Cc: Darren Hart , Bjorn Helgaas , platform-driver-x86@vger.kernel.org, "linux-kernel@vger.kernel.org" , Petri Hodju , Matthew Garrett , "linux-pci@vger.kernel.org" Subject: Re: [Patch v3] apple-gmux: lock iGP IO to protect from vgaarb changes Message-ID: <20150527075329.6df43854@pluto.restena.lu> In-Reply-To: <20150527044749.GB21644@fury.dvhart.com> References: <20150223215155.18444386@neptune.home> <20150303172753.GF83894@vmdeb7> <20150305232038.1873d380@neptune.home> <20150306174254.GB19001@vmdeb7> <20150307011546.0050279d@neptune.home> <20150309225238.0b9ced4e@neptune.home> <20150311223445.6af76f7c@neptune.home> <20150527044749.GB21644@fury.dvhart.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-pci-owner@vger.kernel.org List-ID: Hi Michael, On Tue, 26 May 2015 21:47:49 -0700 Darren Hart wrote: > On Tue, May 26, 2015 at 12:10:48PM -0700, Michael Marineau wrote: > > FYI, this actually broke backlight controls on my MBP11,3 because the > > assumption the patch makes that gmux is always loaded before graphics > > drivers didn't hold true. At least for me dracut included the nouveau > > module in the initrd but not gmux, ensuring the ordering was wrong. No > > errors were reporting, and gmux still offered the backlight device, it > > just became inoperable. I worked around this for my kernel by building > > gmux into vmlinuz instead of as a module but that isn't going to in > > more general configs because there is an apple backlight driver which > > cannot be built at all in that configuration. > > Thank you for reporting this Michael, > > That is tough as nouveau doesn't have an explicit dependency on gmux, so we > could do something like a passive request_module(), but if it isn't in the > initrd image, it would still fail as you describe. > > > Is there a way to make the ordering between nouveau and gmux more > > explicit/reliable? Can gmux complain loudly if the ordering is ever > > wrong? > > It should print an error if the probe fails due to the IO already being in use > or if it can't be allocated. The disabled IO case is only info level though, > perhaps that should be higher priority. Printing something when failing to probe > seems like a reasonable thing to do. > > Michael, which message do you get if you boot with "debug" or "loglevel=6" when > apple-gmux is not built-in? A full kernel log up to including post-initrd loading of gmux would be useful. As far as I have seen nouveau should not be doing unneeded vgaarb operations by itself (though userspace might be) as opposed to closed nvidia driver. If your systems allows, try booting to init=/bin/bash, then check for backlight, load nouveau, check for backlight and finally load gmux and check backlight (putting i915 in the mix where initrd/userspace puts it would be nice). Thanks, Bruno