From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261792AbVFGABl (ORCPT ); Mon, 6 Jun 2005 20:01:41 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261784AbVFGAAs (ORCPT ); Mon, 6 Jun 2005 20:00:48 -0400 Received: from dsl027-180-168.sfo1.dsl.speakeasy.net ([216.27.180.168]:27582 "EHLO sunset.davemloft.net") by vger.kernel.org with ESMTP id S261792AbVFFX6n (ORCPT ); Mon, 6 Jun 2005 19:58:43 -0400 Date: Mon, 06 Jun 2005 16:58:19 -0700 (PDT) Message-Id: <20050606.165819.74748316.davem@davemloft.net> To: jgarzik@pobox.com Cc: gregkh@suse.de, tom.l.nguyen@intel.com, linux-pci@atrey.karlin.mff.cuni.cz, linux-kernel@vger.kernel.org, roland@topspin.com Subject: Re: pci_enable_msi() for everyone? From: "David S. Miller" In-Reply-To: <42A4E213.8050102@pobox.com> References: <42A4D771.7080400@pobox.com> <20050606231325.GA11610@suse.de> <42A4E213.8050102@pobox.com> X-Mailer: Mew version 3.3 on Emacs 21.4 / Mule 5.0 (SAKAKI) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org From: Jeff Garzik Date: Mon, 06 Jun 2005 19:53:55 -0400 > A technology (MSI) allows one to more efficiently call interrupt > handlers, with fewer bus reads... and you want to add a test to each > interrupt handler -- a test which adds several bus reads to the hot path > of every MSI driver? I think he's saying something different. He is saying this test goes in the spot where you select which interrupt handler to register, in place of the current logic which call pci_enable_msi() and checks the return value. MSI unaware drivers are OK because they can only assume looser semantics (shared interrupts possible, no DMA ordering guarentees wrt. interrupt delivery etc.) in their interrupt handlers. So I guess what Greg is proposing is not a bad idea afterall.