From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bombadil.infradead.org ([198.137.202.9]:54169 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752685AbbCSDqX (ORCPT ); Wed, 18 Mar 2015 23:46:23 -0400 Date: Wed, 18 Mar 2015 20:46:18 -0700 From: Darren Hart To: Bruno =?iso-8859-1?Q?Pr=E9mont?= Cc: 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: <20150319034618.GB22993@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> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 In-Reply-To: <20150311223445.6af76f7c@neptune.home> Sender: linux-pci-owner@vger.kernel.org List-ID: On Wed, Mar 11, 2015 at 10:34:45PM +0100, Bruno Prémont wrote: > As GMUX depends on IO for iGP to be enabled and active, lock the IO at > vgaarb level. This should prevent GPU driver for dGPU to disable IO for > iGP while it tries to own legacy VGA IO. > > This fixes usage of backlight control combined with closed nvidia > driver on some Apple dual-GPU (intel/nvidia) systems. > > On those systems loading nvidia driver disables intel IO decoding, > disabling the gmux backlight controls as a side effect. > Prior to commits moving boot_vga from (optional) efifb to less optional > vgaarb this mis-behavior could be avoided by using right kernel config > (efifb enabled but vgaarb disabled). > > This patch explicitly does not try to trigger vgaarb changes in order > to avoid confusing already running graphics drivers. If IO has been > mis-configured by vgaarb gmux will thus fail to probe. > It is expected to load/probe gmux prior to graphics drivers. > > Fixes: ce027dac592c0ada241ce0f95ae65856828ac450 # nvidia interaction > Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=86121 > Reported-by: Petri Hodju > Tested-by: Petri Hodju > Cc: Bjorn Helgaas > Cc: Matthew Garrett > Signed-off-by: Bruno Prémont > --- > Resending v2 in the hope Darren won't hit quoted-printable. > Also adding linux-pci on CC by Bjorn's request in bugzilla. Much better, thanks. Queued. -- Darren Hart Intel Open Source Technology Center