From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754448Ab2ATQQE (ORCPT ); Fri, 20 Jan 2012 11:16:04 -0500 Received: from mail-yx0-f174.google.com ([209.85.213.174]:60937 "EHLO mail-yx0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753682Ab2ATQQC (ORCPT ); Fri, 20 Jan 2012 11:16:02 -0500 Date: Fri, 20 Jan 2012 09:15:57 -0700 From: Grant Likely To: Michael Bohan Cc: Rob Herring , tglx@linutronix.de, Russell King , linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] arm: irq: Allow for specification of no preallocated irqs Message-ID: <20120120161557.GT4223@ponder.secretlab.ca> References: <1327013024-22530-1-git-send-email-mbohan@codeaurora.org> <4F18A18C.9090302@gmail.com> <4F18B577.8080101@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4F18B577.8080101@codeaurora.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 19, 2012 at 04:29:43PM -0800, Michael Bohan wrote: > On 1/19/2012 3:04 PM, Rob Herring wrote: > >No doubt that arch_probe_nr_irqs is doing the wrong thing on ARM, but no > >pre-allocation is not what we want either. We ultimately want > >arch_probe_nr_irqs to return NR_IRQS_LEGACY (16) to reserve IRQ0 (aka > >NO_IRQ) and legacy ISA IRQs. With my series, NR_IRQS is set to > >NR_IRQS_LEGACY for SPARSE_IRQ. You can accomplish the same thing without > >that series by setting .nr_irqs to NR_IRQS for non-DT and to > >NR_IRQS_LEGACY for DT. For platforms to work in single kernel builds, > >they will need to select SPARSE_IRQ. > > One issue here is that IRQ_BITMAP_BITS is defined as a function of > NR_IRQS. Currently, there's a hack in place that arbitrarily tacks > on 8196 bits to the end, giving the max virq supported as 8212 with > your patches. Unfortunately, the system I'm running on will require > higher values than that, so this actually breaks me. Are that many irqs actually going to be in-use at one time? If not, then the driver should use the irq_domain radix tree reverse map anyway. g.