Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966643AbWKOE4I (ORCPT ); Tue, 14 Nov 2006 23:56:08 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S966642AbWKOE4I (ORCPT ); Tue, 14 Nov 2006 23:56:08 -0500 Received: from srv5.dvmed.net ([207.36.208.214]:20961 "EHLO mail.dvmed.net") by vger.kernel.org with ESMTP id S966643AbWKOE4H (ORCPT ); Tue, 14 Nov 2006 23:56:07 -0500 Message-ID: <455A9DE2.8080908@garzik.org> Date: Tue, 14 Nov 2006 23:56:02 -0500 From: Jeff Garzik User-Agent: Thunderbird 1.5.0.8 (X11/20061107) MIME-Version: 1.0 To: Roland Dreier CC: Linus Torvalds , David Miller , linux-kernel@vger.kernel.org, tiwai@suse.de Subject: Re: [PATCH] ALSA: hda-intel - Disable MSI support by default References: <20061114.190036.30187059.davem@davemloft.net> <20061114.192117.112621278.davem@davemloft.net> <455A938A.4060002@garzik.org> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Score: -4.3 (----) X-Spam-Report: SpamAssassin version 3.1.7 on srv5.dvmed.net summary: Content analysis details: (-4.3 points, 5.0 required) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1562 Lines: 39 Roland Dreier wrote: > > That reminds me of a potential driver bug -- MSI-aware drivers need to > > call pci_intx(pdev,0) to turn off the legacy PCI interrupt, before > > enabling MSI interrupts. > > Huh? The device can't generate any legacy interrupts once MSI is > enabled. As the PCI spec says: > > "While enabled for MSI or MSI-X operation, a function is prohibited > from using its INTx# pin (if implemented) to request service (MSI, > MSI-X, and INTx# are mutually exclusive)." > > Although the MSI core does do pci_intx() for PCIe devices only, for > some reason I can't grok. Probably the same reason I just mentioned in a reply to DaveM. Wildly speculating, some chips may depend on software to disable INTX -- i.e. depend on software to provide this aspect of PCI spec compliance. > > The only thing that has changed recently is that people are trying to > > get it working on AMD/NV as well. (Brice Goglin's stuff starting at > > 6397c75cbc4d7dbc3d07278b57c82a47dafb21b5 in 'git log') > > Actually NVidia/AMD was working on some systems long before that -- I > had it working at least 2 years ago. Well, just noting that AMD/NV seems to be a common pattern in the referenced bug reports, and the set of Linux platforms which claim to support MSI had recent churn. Jeff - 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/