Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933653Ab3CSSTC (ORCPT ); Tue, 19 Mar 2013 14:19:02 -0400 Received: from iolanthe.rowland.org ([192.131.102.54]:56271 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S933316Ab3CSSTA (ORCPT ); Tue, 19 Mar 2013 14:19:00 -0400 Date: Tue, 19 Mar 2013 14:18:59 -0400 (EDT) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: Daniel Vetter cc: Chris Wilson , Jiri Kosina , Greg KH , Harald Arnesen , Kernel development list , "Rafael J. Wysocki" , Peter Hurley , Thomas Meyer , Shawn Starr , USB list , , Bjorn Helgaas , , Yinghai Lu , Imre Deak , Daniel Kurtz , , Thomas Gleixner , "H. Peter Anvin" , , Arkadiusz Miskiewicz Subject: Re: gm45 intel gfx can generate non-MSI irq# in MSI mode (was Re: [PATCH] drm/i915: stop using GMBUS IRQs on Gen4 chips (was Re: [3.9-rc1] irq 16: nobody cared (was [3.9-rc1] very poor interrupt respo In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1230 Lines: 26 On Tue, 19 Mar 2013, Daniel Vetter wrote: > > That might be misleading. It's possible that the erroneous IRQs _are_ > > being issued but you're simply not aware of them. If the kernel thinks > > that no device is using IRQ 16 then it will leave that IRQ disabled. > > I guess I should have phrased it more precisely, but that's exactly > what I expect is happening on my machine: I don't have anything on > irq16 (i.e. in non-msi mode the gfx interrupt isn't shared) and hence > the irq is completely disabled. Which obviously makes it impossible > for me to reproduce the issue. To test that theory, is there a quick > way to force-enable a given interrupt, short of just hacking up a 2nd > dummy irq handler in my driver? I don't know of any way. In fact, I have been thinking of writing a test driver module, with a module parameter telling it which IRQ number to register for. It seems like the sort of thing that would be useful to have, from time to time. Alan Stern -- 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/