From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-gx0-f179.google.com (mail-gx0-f179.google.com [209.85.161.179]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority" (not verified)) by ozlabs.org (Postfix) with ESMTPS id 177C1B6FD0 for ; Fri, 13 Jan 2012 11:31:34 +1100 (EST) Received: by ggnf2 with SMTP id f2so1413913ggn.38 for ; Thu, 12 Jan 2012 16:31:31 -0800 (PST) Message-ID: <4F0F7B60.5040701@gmail.com> Date: Thu, 12 Jan 2012 18:31:28 -0600 From: Rob Herring MIME-Version: 1.0 To: Grant Likely Subject: Re: [RFC 13/14] irq_domain: Remove 'new' irq_domain in favour of the ppc one References: <1326313337-24603-1-git-send-email-grant.likely@secretlab.ca> <1326313337-24603-14-git-send-email-grant.likely@secretlab.ca> <4F0DFC0F.2090005@gmail.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Cc: sfr@canb.auug.org.au, Russell King , linux-kernel@vger.kernel.org, Thomas Gleixner , linuxppc-dev@lists.ozlabs.org, "linux-arm-kernel@lists.infradead.org" List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Adding lakml... On 01/11/2012 03:27 PM, Grant Likely wrote: > On Wed, Jan 11, 2012 at 2:15 PM, Rob Herring wrote: >> Grant, >> >> On 01/11/2012 02:22 PM, Grant Likely wrote: >>> This patch removes the simplistic implementation of irq_domains and enables >>> the powerpc infrastructure for all irq_domain users. The powerpc >>> infrastructure includes support for complex mappings between Linux and >>> hardware irq numbers, and can manage allocation of irq_descs. >>> >>> This patch also converts the few users of irq_domain_add()/irq_domain_del() >>> to call irq_domain_add_legacy() instead. >> >> So what is the non-legacy way? Legacy implies we don't want to do it >> that way. I guess until we remove all non-DT platforms with GIC we are >> stuck with legacy. That seems like it could be a ways out until we get >> there. > > Non-legacy is letting the irq_domain manage the irq_desc allocations. > Some of the controllers will be easy to convert, some will be more > difficult. The primary thing that really blocks getting away from the > legacy method is anything that expects hardcoded #defined irq numbers. > The goal is to convert all users over to the linear revmap method. > So I gave this a spin on highbank. I ran into a couple problems. I had to revert "irqdesc: Consolidate irq reservation logic" which is in your branch, but not this series. irq_alloc_desc_from was returning -EEXIST. The GIC code did not work which I think is specific to using gic_of_init which makes irq_start = -1. With that it still doesn't work. It dies in gic_set_type... I've found one problem which I'll reply inline to, but I think this is a dead end path anyway. You have removed the irq_alloc_descs call from the GIC which is a step backwards. Several of the ARM DT enabled platforms are at the point they can fully support dynamic virq base for each irqchip. I changed the domain from legacy to linear and got things working. The issue with linear is for SPARSE_IRQ. The default behavior on ARM for SPARSE_IRQ is all nr_irqs are allocated at boot time before any controller is initialized. The only platform with a GIC and requiring SPARSE_IRQ is shmobile, but it is also the only one that calls irq_alloc_desc functions for it's interrupts. So I think we are okay there. The problem occurs when enabling SPARSE_IRQ for a non-DT platform with a GIC and with irqchips that don't call irq_alloc_desc for their irqs. IMHO, this should be an okay trade-off. There's no advantage to enabling SPARSE_IRQ on ARM for platforms that don't require it. All the platforms with a GIC have active work to convert to DT (except shmobile which I think is okay), so it's a temporary issue. Rob