From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757855Ab2K0Bl5 (ORCPT ); Mon, 26 Nov 2012 20:41:57 -0500 Received: from e28smtp09.in.ibm.com ([122.248.162.9]:51767 "EHLO e28smtp09.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757838Ab2K0Blz (ORCPT ); Mon, 26 Nov 2012 20:41:55 -0500 Message-ID: <1353980506.2309.13.camel@localhost> Subject: Re: [PATCH] No need to call irq_domain_legacy_revmap() for twice From: Mike To: Grant Likely Cc: linux-kernel@vger.kernel.org, tglx@linutronix.de, benh@kernel.crashing.org Date: Tue, 27 Nov 2012 09:41:46 +0800 In-Reply-To: <20121126201739.13F213E09C2@localhost> References: <1348479475-13074-1-git-send-email-qiudayu@linux.vnet.ibm.com> <20121126201739.13F213E09C2@localhost> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3 (3.2.3-3.fc16) Content-Transfer-Encoding: 8bit Mime-Version: 1.0 x-cbid: 12112701-2674-0000-0000-000006E2E220 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 在 2012-11-26一的 20:17 +0000，Grant Likely写道： > On Mon, 24 Sep 2012 17:37:55 +0800, Mike Qiu wrote: > > Function irq_create_mapping() calls irq_find_mapping(). The later > > function has checked if the indicated IRQ domain has hw IRQ mapped to > > virtual IRQ through legacy mode or not and return the value of the > > legacy irq number by call irq_domain_legacy_revmap(). We needn't > > to call irq_domain_legacy_revmap() to do same check in > > irq_create_mapping() again. > > > > The patch removes the duplicate call. > > > > Signed-off-by: Mike Qiu > > --- > > kernel/irq/irqdomain.c | 7 +++++-- > > 1 files changed, 5 insertions(+), 2 deletions(-) > > > > diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c > > index 49a7772..286d672 100644 > > --- a/kernel/irq/irqdomain.c > > +++ b/kernel/irq/irqdomain.c > > @@ -547,9 +547,12 @@ unsigned int irq_create_mapping(struct irq_domain *domain, > > return virq; > > } > > > > - /* Get a virtual interrupt number */ > > + /* > > + * For IRQ domain with type of IRQ_DOMAIN_MAP_LEGACY, we needn't > > + * create the IRQ mapping for non-existing one, so just return 0. > > + */ > > if (domain->revmap_type == IRQ_DOMAIN_MAP_LEGACY) > > - return irq_domain_legacy_revmap(domain, hwirq); > > + return 0; > > But it does need to return the virq assigned to the hwirq. That is why > it has to call the revmap function. > Yes, thanks this judgment has been done in /*Check if mapping already exists*/ virq = irq_find_mapping(domain, hwirq); if the virq equals none zero, the func irq_create_mapping will return the virq value directly(already exists). otherwise, that means virq equals zero, this has two meanings, one is haven't find the already exist mapping, the other one is in irq_find_mapping() case IRQ_DOMAIN_MAP_LEGACY: return irq_domain_legacy_revmap(domain, hwirq); this may return zero. So, when we check if it is a IRQ_DOMAIN_MAP_LEGACY, we just return zero is OK. because if it is none zero, it will be return after check if mapping already exists, and never come here. also we never try to assign the virq for the legacy map. I don't know if you have understand my explanation. Thanks Mike > g. >