Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932103AbaKXOdc (ORCPT ); Mon, 24 Nov 2014 09:33:32 -0500 Received: from mga03.intel.com ([134.134.136.65]:51514 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753356AbaKXOdb (ORCPT ); Mon, 24 Nov 2014 09:33:31 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.07,449,1413270000"; d="scan'208";a="642588583" Message-ID: <547341AA.9070506@linux.intel.com> Date: Mon, 24 Nov 2014 22:33:14 +0800 From: Jiang Liu Organization: Intel User-Agent: Mozilla/5.0 (Windows NT 6.2; WOW64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 MIME-Version: 1.0 To: "Yun Wu (Abel)" CC: Thomas Gleixner , LKML , Bjorn Helgaas , Grant Likely , Marc Zyngier , Yingjoe Chen , Yijing Wang Subject: Re: [patch 01/16] irqdomain: Introduce new interfaces to support hierarchy irqdomains References: <20141112133941.647950773@linutronix.de> <20141112134119.881823615@linutronix.de> <547325A9.3000109@huawei.com> <54733A4E.8020304@huawei.com> <54733C7D.2010405@linux.intel.com> <54733E7C.60005@huawei.com> In-Reply-To: <54733E7C.60005@huawei.com> 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 On 2014/11/24 22:19, Yun Wu (Abel) wrote: > On 2014/11/24 22:11, Jiang Liu wrote: > >> On 2014/11/24 22:01, Yun Wu (Abel) wrote: >>> On 2014/11/24 21:13, Thomas Gleixner wrote: >>> >>>> On Mon, 24 Nov 2014, Yun Wu (Abel) wrote: >>>>> Hi Thomas, Jiang, >>>>> On 2014/11/12 21:42, Thomas Gleixner wrote: >>>>> >>>>>> From: Jiang Liu >>>>>> >>>>> [...] >>>>>> /* Number of irqs reserved for a legacy isa controller */ >>>>>> #define NUM_ISA_INTERRUPTS 16 >>>>>> @@ -64,6 +66,16 @@ struct irq_domain_ops { >>>>>> int (*xlate)(struct irq_domain *d, struct device_node *node, >>>>>> const u32 *intspec, unsigned int intsize, >>>>>> unsigned long *out_hwirq, unsigned int *out_type); >>>>>> + >>>>>> +#ifdef CONFIG_IRQ_DOMAIN_HIERARCHY >>>>>> + /* extended V2 interfaces to support hierarchy irq_domains */ >>>>>> + int (*alloc)(struct irq_domain *d, unsigned int virq, >>>>>> + unsigned int nr_irqs, void *arg); >>>>>> + void (*free)(struct irq_domain *d, unsigned int virq, >>>>>> + unsigned int nr_irqs); >>>>>> + void (*activate)(struct irq_domain *d, struct irq_data *irq_data); >>>>>> + void (*deactivate)(struct irq_domain *d, struct irq_data *irq_data); >>>>> >>>>> What's the usage of the parameter domain reference in activate/deactivate? >>>>> I think the purpose of the two callbacks is to activate/deactivate the >>>>> irq_data->hwirq in irq_data->domain. If so, the first parameter @domain is >>>>> required to be equal to irq_data->domain (which makes @domain useless). >>>>> Besides, the main responsibility of interrupt domains is to manage mappings >>>>> between hardware and linux interrupt numbers, so would it be better if move >>>>> the two callbacks into struct irq_chip? >>>> >>>> No. It's not a function of the irq_chip to activate/deactivate a >>>> hierarchy. As I explained you before: >>>> >>>> The existing irqdomain code maps between hardware and virtual >>>> interrupts and thereby activates the interrupt in hardware. >>>> >>>> In the hierarchical case we do not touch the hardware in the >>>> allocation step, so we need to activate the allocated interrupt in the >>>> hardware before we can use it. And that's clearly a domain interface >>>> not a irq chip issue. >>>> >>> >>> Makes sense, now the interrupt domain seems to be the best place. >>> And when the @domain parameter can be really useful? I haven't see >>> anyone using it so far. >> We will use it for IOAPIC on x86, as below: >> void mp_irqdomain_deactivate(struct irq_domain *domain, >> struct irq_data *irq_data) >> { >> ioapic_mask_entry(mp_irqdomain_ioapic_idx(domain), >> (int)irq_data->hwirq); >> } >> >> >From an object oriented point of view, we pass the object as the >> first parameter. It's true that we could retrieve domain from >> irq_data->domain instead of explicitly passing it in, but that >> will cause irqdomain interfaces depends on irq_data, not sounds >> a good situation:) > > Hi Gerry, > > Is there any possibility that domain doesn't equal to irq_data->domain? > I'm a little confused.. Hi Yun, Currently they are always the same, but we don't want irqdomain interfaces make assumption of struct irq_data. If it will bring big performance improvement, we will try to kill the first parameter, otherwise we may prefer keeping irqdomain interfaces clear. Thanks! Gerry -- 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/