From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751191Ab1L3Pav (ORCPT ); Fri, 30 Dec 2011 10:30:51 -0500 Received: from mail-gy0-f174.google.com ([209.85.160.174]:61642 "EHLO mail-gy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750863Ab1L3Pat (ORCPT ); Fri, 30 Dec 2011 10:30:49 -0500 Message-ID: <4EFDD925.3050806@gmail.com> Date: Fri, 30 Dec 2011 09:30:45 -0600 From: Rob Herring User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:8.0) Gecko/20111124 Thunderbird/8.0 MIME-Version: 1.0 To: David Daney CC: Thomas Gleixner , devicetree-discuss@lists.ozlabs.org, Grant Likely , Rob Herring , linux-mips@linux-mips.org, linux-kernel@vger.kernel.org, David Daney Subject: Re: [PATCH v2 0/4] irq/of: Cleanup and Enchance irq_domain support. References: <1323916330-8865-1-git-send-email-ddaney.cavm@gmail.com> In-Reply-To: <1323916330-8865-1-git-send-email-ddaney.cavm@gmail.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org David, On 12/14/2011 08:32 PM, David Daney wrote: > From: David Daney > > Back in early Nov. I send the first version of this patch set. Now > things are heating up again in the world of irq_domain, so I wanted to > try to get some closure on the issues I had. The Octeon patch is > included here to show how I am using irq_domain, but is part of a much > larger effort to merge Octeon device tree support. > > The basic problem I am attempting to solve is using irq domains when > there is a 'non-linear' mapping of hwirq <--> irq within a domain. > Octeon has a single set of irq numbers that is used across two > different implementations of the interrupt controller as well as more > than 10 different SOCs all which use different subsets of the irq > number space. The result is that the hwirq to irq mapping function > contains many gaps and discontinuities, it is really quite random. > > The existing irq domain infrastructure assumes a continuous linear > mapping of hwirq to irq that can be encapsulated by the irq_base, > hwirq_base and nr_irq elements of struct irq_domain. This is not > suitable for the Octeon implementation. > > The gist of my change is to add an optional iterator function to > irq_domain_ops which knows how to iterate over the irq numbers in a > given domain. For simple linear domains (those currently supported), > we iterate using the current method based on irq_base, hwirq_base and > nr_irq. > > Summary of the patches: > > 1) Get rid of some unused code to make subsequent changes simpler. > > 2) Cleanup the data type used by various hwirq functions and users. > > 3) Add the irq iterator, and fix up the ARM GIC code to use it instead > of the current irq_domain_for_each_irq(). > > 4) Add the Octeon users of the interface. > > In an earlier exchange, Rob Herring had said: > > ... Handling sparse irqs is a potentially common problem, so we > should address that in the core irqdomain code. > > Which is what this patch set is doing. > > There was a suggestion that perhaps having .to_irq() return a magic > value if there was no mapping would also work. However I prefer this > approach as it separates the concepts of iteration and mapping of irq > numbers. > > Please comment. Can we first have a patch that just allows irq domains to be enabled on MIPS. It collides because of multiple versions of irq_create_of_mapping. Rob