From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alan Cox Subject: Re: [Bulk] Re: [PATCH 1/2] [PCI] Check that MWI bit really did get set Date: Sun, 15 Oct 2006 22:52:15 +0100 Message-ID: <1160949135.5732.85.camel@localhost.localdomain> References: <1160161519800-git-send-email-matthew@wil.cx> <20061013214135.8fbc9f04.akpm@osdl.org> <20061014140249.GL11633@parisc-linux.org> <20061014134855.b66d7e65.akpm@osdl.org> <20061015032000.GP11633@parisc-linux.org> <20061015070809.978C714552@adsl-69-226-248-13.dsl.pltn13.pacbell.net> <1160922082.5732.51.camel@localhost.localdomain> <20061015135756.GD22289@parisc-linux.org> <20061015104544.5de31608.akpm@osdl.org> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: Matthew Wilcox , David Brownell , val_henson@linux.intel.com, netdev@vger.kernel.org, linux-pci@atrey.karlin.mff.cuni.cz, linux-kernel@vger.kernel.org, gregkh@suse.de Return-path: Received: from outpipe-village-512-1.bc.nu ([81.2.110.250]:37804 "EHLO lxorguk.ukuu.org.uk") by vger.kernel.org with ESMTP id S1750997AbWJOV0F (ORCPT ); Sun, 15 Oct 2006 17:26:05 -0400 To: Andrew Morton In-Reply-To: <20061015104544.5de31608.akpm@osdl.org> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Ar Sul, 2006-10-15 am 10:45 -0700, ysgrifennodd Andrew Morton: > If the drivers doesn't care and if it makes no difference to performance > then just delete the call to pci_set_mwi(). > > But if MWI _does_ make a difference to performance then we should tell > someone that it isn't working rather than silently misbehaving? It isn't misbehaving it just isn't available. MWI is rather different to say pci_set_master() in that it makes a lot of sense for many drivers to ask for it but not care about the results. Something like pci_set_master failing is a big problem and has to be handled (although as we often don't use BIOS PCI services we see fake success in some cases). MWI is an "extra cheese" option not a "no pizza" case Alan