Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753281AbbF3MRf (ORCPT ); Tue, 30 Jun 2015 08:17:35 -0400 Received: from foss.arm.com ([217.140.101.70]:41298 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753195AbbF3MRU (ORCPT ); Tue, 30 Jun 2015 08:17:20 -0400 Message-ID: <559288CA.40605@arm.com> Date: Tue, 30 Jun 2015 13:17:14 +0100 From: Marc Zyngier Organization: ARM Ltd User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Icedove/31.7.0 MIME-Version: 1.0 To: Hanjun Guo , Lorenzo Pieralisi CC: Jason Cooper , Will Deacon , Catalin Marinas , "Rafael J. Wysocki" , Thomas Gleixner , Jiang Liu , Arnd Bergmann , Tomasz Nowicki , "grant.likely@linaro.org" , Olof Johansson , Wei Huang , "linux-arm-kernel@lists.infradead.org" , "linux-acpi@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linaro-acpi@lists.linaro.org" Subject: Re: [PATCH v2 6/9] irqchip / gic: Add stacked irqdomain support for ACPI based GICv2 init References: <1434703572-26221-1-git-send-email-hanjun.guo@linaro.org> <1434703572-26221-7-git-send-email-hanjun.guo@linaro.org> <20150622172014.GB26129@red-moon> <5589772A.8070708@linaro.org> <20150623173845.GC31466@red-moon> <558E1DEE.3090900@linaro.org> <55910440.8070702@arm.com> <559282A0.8090601@linaro.org> In-Reply-To: <559282A0.8090601@linaro.org> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3353 Lines: 80 On 30/06/15 12:50, Hanjun Guo wrote: > Hi Marc, > > On 06/29/2015 04:39 PM, Marc Zyngier wrote: >> On 27/06/15 04:52, Hanjun Guo wrote: >>> On 06/24/2015 01:38 AM, Lorenzo Pieralisi wrote: >>>> On Tue, Jun 23, 2015 at 04:11:38PM +0100, Hanjun Guo wrote: > [...] >>>> >>>>>>> for (i = 0; i < nr_irqs; i++) >>>>>>> gic_irq_domain_map(domain, virq + i, hwirq + i); >>>>>>> @@ -945,11 +952,11 @@ void __init gic_init_bases(unsigned int gic_nr, int irq_start, >>>>>>> gic_irqs = 1020; >>>>>>> gic->gic_irqs = gic_irqs; >>>>>>> >>>>>>> - if (node) { /* DT case */ >>>>>>> + if (node || !acpi_disabled) { /* DT or ACPI case */ >>>>>>> gic->domain = irq_domain_add_linear(node, gic_irqs, >>>>>>> &gic_irq_domain_hierarchy_ops, >>>>>>> gic); >>>> >>>> I think this is a bit more worrying, I mean passing a NULL node pointer to >>>> the irqdomain layer which basically means you are booting out of ACPI >>> >>> I'm little confused here, would you mind explaining more for your >>> worrying? To me, node pointer is optional and it's ok for ACPI >>> case. >>> >>>> (for you, if that's true for the irq_domain_add_linear implementation >>>> that's another story), the node pointer should be optional but you >>>> need feedback from IRQ layer maintainers here. >>> >>> Sure. >> >> Frankly, I'd really like to see ACPI using the "node" parameter for >> something useful. This would save having to cache pointers all over the >> place, will make find_irq_host() work as expected... etc. >> >> See the comment at the top of linux/irqdomain.h : >> >> "... This code could thus be used on other architectures by replacing >> those two by some sort of arch-specific void * "token" used to identify >> interrupt controllers." > > To init GIC in ACPI, we can only use the table entry pointer as > the token, but the ACPI static tables are early mem/io remapped > memory at boot stage, and it will be not available after boot, > also we need muti types of MADT enties to init GIC (GICC and GICD > for GICv2, GICC or GICR and GICD for GICv3), not as DT, just > one single node to include all the information needed to init > the GIC. A single pointer would be enough, you don't need all of them. > We use ACPI handle for devices as node for DT when the namespace > is available, but that's pretty late in the boot stage which GIC, > SMP and timers were already initialized, so ACPI handle can not > use as the token too. > > I see multi places just pass NULL as the pointer directly for > irq_domain_add_linear() which works fine, and for ACPI, we tested > this patch and also it works. Yes it works. But you're reinventing the wheel by keeping references outside of the normal framework, which is simply going to make the code more difficult to maintain in the long run. Putting NULL as the device_node parameter really means "this is a domain I don't need to look up later". In your case, you will have to lookup that domain, all the time. You're just doing it in your own little corner, which is what bothers me. M. -- Jazz is not dead. It just smells funny... -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/