Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964910AbWEBQOw (ORCPT ); Tue, 2 May 2006 12:14:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964912AbWEBQOw (ORCPT ); Tue, 2 May 2006 12:14:52 -0400 Received: from atlrel7.hp.com ([156.153.255.213]:11430 "EHLO atlrel7.hp.com") by vger.kernel.org with ESMTP id S964910AbWEBQOv (ORCPT ); Tue, 2 May 2006 12:14:51 -0400 From: Bjorn Helgaas To: linux-pci@atrey.karlin.mff.cuni.cz Subject: Re: Add a "enable" sysfs attribute to the pci devices to allow userspace (Xorg) to enable devices without doing foul direct access Date: Tue, 2 May 2006 10:14:45 -0600 User-Agent: KMail/1.8.3 Cc: Dave Airlie , Arjan van de Ven , Andrew Morton , greg@kroah.com, linux-kernel@vger.kernel.org, pjones@redhat.com References: <1146300385.3125.3.camel@laptopd505.fenrus.org> <1146301148.3125.7.camel@laptopd505.fenrus.org> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200605021014.45684.bjorn.helgaas@hp.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1647 Lines: 35 On Saturday 29 April 2006 03:04, Dave Airlie wrote: > > > This patch adds an "enable" sysfs attribute to each PCI device. When read it > > shows the "enabled-ness" of the device, but you can write a "0" into it to > > disable a device, and a "1" to enable it. > > > > This later is needed for X and other cases where userspace wants to enable > > the BARs on a device (typical example: to run the video bios on a secundary > > head). Right now X does all this "by hand" via bitbanging, that's just evil. > > This allows X to no longer do that but to just let the kernel do this. > > > > Signed-off-by: Arjan van de Ven > > CC: Peter Jones > > CC: Dave Airlie > > ACK > > This would allow me to remove the issue in X where loading the DRM at X > startup acts differently than loading the DRM before X runs, due to Xs PCI > probe running in-between... with this I can just enable all VGA devices > and no worry whether they have a DRM or not.. This sysfs "enable" patch seems like goodness. But I hope that when X uses this, it only enables & disables VGA devices it's actually using. In the past, it seems like X has blindly disabled *all* VGA devices in the system, even though they might be in use by another X server. I'm sure that's all well-understood and cleaned up now; just wanted to make sure this nightmare didn't recur. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/