Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752331AbXJVXkc (ORCPT ); Mon, 22 Oct 2007 19:40:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750968AbXJVXkW (ORCPT ); Mon, 22 Oct 2007 19:40:22 -0400 Received: from khc.piap.pl ([195.187.100.11]:57618 "EHLO khc.piap.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750798AbXJVXkV (ORCPT ); Mon, 22 Oct 2007 19:40:21 -0400 To: Jeff Garzik Cc: Daniel Barkalow , Linas Vepstas , Shane Huang , davem@davemloft.net, gregkh@suse.de, htejun@gmail.com, brice.goglin@gmail.com, david.gaarenstroom@gmail.com, linux-kernel@vger.kernel.org, linux-pci@atrey.karlin.mff.cuni.cz, shane.huang@amd.com, linux-ide@vger.kernel.org, Brice Goglin Subject: Re: [patch] PCI: disable MSI on more ATI NorthBridges References: <20071019195749.GK29903@austin.ibm.com> <471911BE.2000405@garzik.org> <471D0ADC.7000005@garzik.org> From: Krzysztof Halasa Date: Tue, 23 Oct 2007 01:40:18 +0200 In-Reply-To: <471D0ADC.7000005@garzik.org> (Jeff Garzik's message of "Mon, 22 Oct 2007 16:41:00 -0400") Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1646 Lines: 44 Jeff Garzik writes: > Note that INTX_DISABLE is a recent addition to PCI. It's PCI 2.3. > Older PCI devices > support neither MSI nor INTX-disable, so make sure such devices don't > creep into your sample. MSI has been introduced by PCI 2.2 (and thus PCI-X 1.0) so there may be devices with MSI but without INTx-disable bit. I guess I have some early PCI-X hardware with MSI but I don't know if they have INTx-disable bit and I can't currently test that. And it probably doesn't matter. > In general it is documented that INTX_DISABLE should apply only to > INTx# so devices that disable MSI based on that bit are out of spec. The wording is: 10: This bit disables the device from asserting INTx#. A value of 0 enables the assertion of its INTx# signal. A value of 1 disables the assertion of its INTx# signal. This bit's state after RST# is 0. Refer to Section 6.8.1.3 for control of MSI. So strictly speaking it mandates disabling/enabling INTx but says nothing about other things (e.g. MSI). Some common sense dictates it shouldn't disable MSI, I guess. The "MSI Enable" description doesn't leave any doubt: 0: MSI Enable: If 1, the function is permitted to use MSI to request service and is prohibited from using its INTx# pin [...] > But unfortunately that is rather irrelevant, since we see these > out-of-spec devices in the field today. Right. -- Krzysztof Halasa - 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/