Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263506AbTEMLJM (ORCPT ); Tue, 13 May 2003 07:09:12 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263571AbTEMLJM (ORCPT ); Tue, 13 May 2003 07:09:12 -0400 Received: from jurassic.park.msu.ru ([195.208.223.243]:23308 "EHLO jurassic.park.msu.ru") by vger.kernel.org with ESMTP id S263506AbTEMLJK (ORCPT ); Tue, 13 May 2003 07:09:10 -0400 Date: Tue, 13 May 2003 15:21:26 +0400 From: Ivan Kokshaysky To: Matt Porter Cc: Matthew Wilcox , Jeff Garzik , linux-kernel@vger.kernel.org, davem@redhat.com Subject: Re: Message Signalled Interrupt support? Message-ID: <20030513152126.A16419@jurassic.park.msu.ru> References: <20030512163249.GF27111@gtf.org> <20030512165331.GZ29534@parcelfarce.linux.theplanet.co.uk> <20030512104300.A23510@home.com> <20030512182023.GA29534@parcelfarce.linux.theplanet.co.uk> <20030512114851.B23510@home.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i In-Reply-To: <20030512114851.B23510@home.com>; from mporter@kernel.crashing.org on Mon, May 12, 2003 at 11:48:51AM -0700 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1635 Lines: 53 On Mon, May 12, 2003 at 11:48:51AM -0700, Matt Porter wrote: > request_msi() needs an additional parameter to specify which MSI > it is hooking. A device can implement many messages in order to > clarify which one of many events on a device has occurred. It > may be desired to hook a separate handler for each of those to > avoid another read of a status register. Assuming that platform specific PCI setup does reasonable real to virtual IRQ mapping, request_msi() is not needed. We can use pdev->irq as "base" vector and MSI message number as offset. Alpha works this way, BTW. I think of something like this: /** * pci_using_msi - is this PCI device configured to use MSI? * @dev: PCI device structure of device being queried * * Tells whether or not a PCI device is configured to use Message Signaled * Interrupts. Returns number of allocated MSI messages, else 0. */ int pci_using_msi(struct pci_dev *dev) { int msi = pci_find_capability(dev, PCI_CAP_ID_MSI); u8 msgctl; if (!msi || !dev->irq) return 0; pci_read_config_byte(dev, msi + PCI_MSI_FLAGS, &msgctl); if (!(msgctl & PCI_MSI_FLAGS_ENABLE)) return 0; return 1 << ((msgctl >> 4) & 7); /* # of messages allocated */ } So that MSI-aware driver can do nummsgs = pci_using_msi(dev); if (!nummsgs) goto no_msi; for (msg = 0; msg < nummsgs; msg++) { ... request_irq(dev->irq + msg, ...); } Ivan. - 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/