Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754549Ab3CRS5N (ORCPT ); Mon, 18 Mar 2013 14:57:13 -0400 Received: from mail-ia0-f172.google.com ([209.85.210.172]:59327 "EHLO mail-ia0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753168Ab3CRS5K (ORCPT ); Mon, 18 Mar 2013 14:57:10 -0400 MIME-Version: 1.0 In-Reply-To: References: <1460519.ejNFI1DrGk@vostro.rjw.lan> <1363280764.26318.4.camel@thor.lan> <5657408.cYX6iimiA4@vostro.rjw.lan> <5142E7F0.4020002@gmail.com> Date: Mon, 18 Mar 2013 11:57:09 -0700 X-Google-Sender-Auth: geAx7FfSEO3HPXmZxRmaVRSBVU8 Message-ID: Subject: Re: [3.9-rc1] irq 16: nobody cared (was [3.9-rc1] very poor interrupt responses) From: Yinghai Lu To: Jiri Kosina Cc: 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, Daniel Vetter , Imre Deak , Daniel Kurtz , dri-devel@lists.freedesktop.org Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1741 Lines: 45 On Mon, Mar 18, 2013 at 2:12 AM, 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. What is /proc/interrupts difference between with and without pci=nomsi ? drm is forced to share irq 16? Thanks Yinghai -- 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/