From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755114Ab2GRQwn (ORCPT ); Wed, 18 Jul 2012 12:52:43 -0400 Received: from smtp.ctxuk.citrix.com ([62.200.22.115]:11794 "EHLO SMTP.EU.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751459Ab2GRQwl (ORCPT ); Wed, 18 Jul 2012 12:52:41 -0400 X-IronPort-AV: E=Sophos;i="4.77,610,1336348800"; d="scan'208";a="13593768" Date: Wed, 18 Jul 2012 17:51:55 +0100 From: Stefano Stabellini X-X-Sender: sstabellini@kaball.uk.xensource.com To: Konrad Rzeszutek Wilk CC: Stefano Stabellini , "linux-kernel@vger.kernel.org" , "xen-devel@lists.xensource.com" , Ian Campbell , "Tim (Xen.org)" Subject: Re: [PATCH WIP 6/6] xen/arm: enable evtchn irqs In-Reply-To: <20120716145709.GB552@phenom.dumpdata.com> Message-ID: References: <1340381685-22529-1-git-send-email-stefano.stabellini@eu.citrix.com> <1340381685-22529-6-git-send-email-stefano.stabellini@eu.citrix.com> <20120709144005.GA12102@phenom.dumpdata.com> <20120716145709.GB552@phenom.dumpdata.com> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 16 Jul 2012, Konrad Rzeszutek Wilk wrote: > On Fri, Jul 13, 2012 at 06:14:33PM +0100, Stefano Stabellini wrote: > > On Mon, 9 Jul 2012, Konrad Rzeszutek Wilk wrote: > > > On Fri, Jun 22, 2012 at 05:14:45PM +0100, Stefano Stabellini wrote: > > > > On ARM irqs are not enabled by default: > > > > > > Which IRQs? Xen IRQs? Linux IRQs? > > > > Linux IRQs > > > > > > > > - call enable_percpu_irq for IRQ_EVTCHN_CALLBACK; > > > > > > Why do we want to do that? > > > > drivers are supposed to call enable_irq after request_irq, however on > > x86 we could get away without it because Linux irqs are enabled by > > default (see below) > > > > > > > > - set the IRQF_VALID flag for the other irqs bound to evtchns. It causes > > > > IRQ_NOAUTOEN to be set and as a consequence irq_unmask is going to be > > > > called when a xenbus driver calls request_irq. > > > > > > Can you explain in more details why we need that? > > > > If _IRQ_NOAUTOEN is set, irq_settings_can_autoenable returns false and > > __setup_irq doesn't call irq_startup. > > > > IRQ_NOAUTOEN is set by default by set_irq_flags on ARM, but not on x86. > > OK, please include those questions/answers in the git commit and > repost. --- xen/arm: enable evtchn irqs On ARM Linux irqs are not enabled by default: - call enable_percpu_irq for IRQ_EVTCHN_CALLBACK (drivers are supposed to call enable_irq after request_irq); - set the IRQF_VALID flag for the other irqs bound to evtchns. It causes IRQ_NOAUTOEN to be set and as a consequence irq_unmask is going to be called when a xenbus driver calls request_irq. This is needed because IRQ_NOAUTOEN is set by set_irq_flags on ARM. If IRQ_NOAUTOEN is set __setup_irq doesn't call irq_startup that is responsible for calling irq_unmask at startup time. Signed-off-by: Stefano Stabellini diff --git a/drivers/xen/events.c b/drivers/xen/events.c index eae0d0b..ca92755 100644 --- a/drivers/xen/events.c +++ b/drivers/xen/events.c @@ -53,6 +53,7 @@ #include #include #include +#include /* * This lock protects updates to the following mapping and reference-count @@ -824,6 +828,7 @@ int bind_evtchn_to_irq(unsigned int evtchn) xen_irq_info_evtchn_init(irq, evtchn); } + set_irq_flags(irq, IRQF_VALID); out: mutex_unlock(&irq_mapping_update_lock); @@ -1748,6 +1753,7 @@ int __init xen_init_IRQ_arm(void) if (rc) { printk(KERN_ERR "Error requesting IRQ %d\n", IRQ_EVTCHN_CALLBACK); } + enable_percpu_irq(IRQ_EVTCHN_CALLBACK, 0); return rc; } core_initcall(xen_init_IRQ_arm);