Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754658Ab3CRT5v (ORCPT ); Mon, 18 Mar 2013 15:57:51 -0400 Received: from mga11.intel.com ([192.55.52.93]:25728 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753170Ab3CRT5t (ORCPT ); Mon, 18 Mar 2013 15:57:49 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.84,865,1355126400"; d="scan'208";a="304663840" Date: Mon, 18 Mar 2013 19:57:32 +0000 From: Chris Wilson To: Jiri Kosina , Yinghai Lu , Harald Arnesen , Kernel development list , "Rafael J. Wysocki" , Peter Hurley , Alan Stern , Thomas Meyer , Shawn Starr , USB list , linux-acpi@vger.kernel.org, Bjorn Helgaas , linux-pci@vger.kernel.org, Imre Deak , Daniel Kurtz , dri-devel@lists.freedesktop.org Subject: Re: [3.9-rc1] irq 16: nobody cared (was [3.9-rc1] very poor interrupt responses) Message-ID: <20130318195728.GA3872@cantiga.alporthouse.com> Mail-Followup-To: Chris Wilson , Jiri Kosina , Yinghai Lu , Harald Arnesen , Kernel development list , "Rafael J. Wysocki" , Peter Hurley , Alan Stern , Thomas Meyer , Shawn Starr , USB list , linux-acpi@vger.kernel.org, Bjorn Helgaas , linux-pci@vger.kernel.org, Imre Deak , Daniel Kurtz , dri-devel@lists.freedesktop.org References: <1460519.ejNFI1DrGk@vostro.rjw.lan> <1363280764.26318.4.camel@thor.lan> <5657408.cYX6iimiA4@vostro.rjw.lan> <5142E7F0.4020002@gmail.com> <20130318191903.GS9021@phenom.ffwll.local> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130318191903.GS9021@phenom.ffwll.local> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2418 Lines: 54 On Mon, Mar 18, 2013 at 08:19:03PM +0100, Daniel Vetter wrote: > On Mon, Mar 18, 2013 at 10:12:49AM +0100, Jiri Kosina wrote: > > On Fri, 15 Mar 2013, Yinghai Lu wrote: > > > > > > Just a datapoint -- I have put a trivial debugging patch in place, and it > > > > reveals that "nobody cared" for irq 16 happens long after last > > > > > > > > I915_WRITE(GMBUS4 + reg_offset, 0); > > > > > > > > has been performed in gmbus_wait_hw_status(). On the other hand, if I > > > > comment out both GMBUS4 register offset writes in gmbus_wait_hw_status(), > > > > then it of course falls back to GPIO bit-banging, but the "nobody cared" > > > > for irq 16 is gone. > > > > > > > > So it seems like something gets severely confused by the I915_WRITE to > > > > GMBUS4 + reg_offset. So far this seems to have been reported solely on > > > > Lenovos as far as I can see (although a completely different types), so it > > > > might be some platform-specific quirk? > > > > > > > > Honestly, I still don't understand how all the GMBUS stuff relates to IRQ > > > > 16 at all. > > > > > > that device is using > > > i915 0000:00:02.0: irq 44 for MSI/MSI-X > > > > > > so can you try to boot with pci=nomsi? > > > > Yes, switching from MSI to IO-APIC-fasteoi makes the report about lost > > interrupts go away. > > > > My understanding from the other mail is that DAniel Vetter already has an > > idea what might be going wrong with IRQ acking on GM45 chipsets; hopefully > > this datapoint regarding MSI will fit into it. > > Yep, there's a big comment in the irq handler for that chipset that we > have a gaping race with when using MSI interrupts. Although the comment > bodly claims that the race is small enough to avoid the dreaded "nobody > cared" message. Looks like gmbus is good at hitting that race - on newer > chips it already brought up a similar race in handling pch interrupts. > > Can you please give the below patch a whirl? It removes the probably race > msi race avoidance code and replaces it with the same trick Paulo used to > fix pch irq handling races. Still nobody cares about irq16. -Chris -- Chris Wilson, Intel Open Source Technology Centre -- 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/