From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964821AbXBLJg3 (ORCPT ); Mon, 12 Feb 2007 04:36:29 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964824AbXBLJg2 (ORCPT ); Mon, 12 Feb 2007 04:36:28 -0500 Received: from caramon.arm.linux.org.uk ([217.147.92.249]:4823 "EHLO caramon.arm.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964821AbXBLJg1 (ORCPT ); Mon, 12 Feb 2007 04:36:27 -0500 Date: Mon, 12 Feb 2007 09:35:49 +0000 From: Russell King To: David Gibson , Thomas Gleixner , mingo@elte.hu, Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: genirq: Add a set_irq_handler_locked() function Message-ID: <20070212093549.GA22465@flint.arm.linux.org.uk> Mail-Followup-To: David Gibson , Thomas Gleixner , mingo@elte.hu, Andrew Morton , linux-kernel@vger.kernel.org References: <20070207023353.GC23870@localhost.localdomain> <1170940949.3646.1.camel@chaos> <20070209034842.GF3489@localhost.localdomain> <20070209073640.GA29988@flint.arm.linux.org.uk> <20070212031728.GA30401@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070212031728.GA30401@localhost.localdomain> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Feb 12, 2007 at 02:17:28PM +1100, David Gibson wrote: > On Fri, Feb 09, 2007 at 07:36:40AM +0000, Russell King wrote: > > On Fri, Feb 09, 2007 at 02:48:42PM +1100, David Gibson wrote: > > > At present set_irq_handler() and all the existing variants take the > > > desc->lock for the irq in question before adjusting the irq's flow > > > handler. This can cause problems for irq chips for which a given > > > interrupt can be either level or edge depending on what's attached. > > > > Are you sure you need to change the flow handler depending on how > > you program the device? > > > > Since the outset of this design, I've had what are essentially edge > > based interrupt sources using the "level" handlers because they haven't > > had a "broken" edge implementation. By that, I mean that the masking > > is done in such a way that you miss edges when the source is masked. > > > > If you do not miss edges while the source is masked, there's no point > > in having the complexity of the "edge" based handler in the path - it > > buys you nothing. Just use the "level" handler instead. > > I see... how terribly obvious. Do you have a better way of naming the functions? > As far as I know, the 4xx UIC does things correctly, though I don't > have handy any devices with edge interrupts to test it with. > > It would still be nice to have this change, so we can use the > lazy-masking from handle_edge_irq(), but I guess I can do without it > for now. If you have correct behaviour from your interrupt controller for edge based interrupts, you don't need the lazy masking, so why make things complicated in this way? -- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: