From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754850AbbCFBfZ (ORCPT ); Thu, 5 Mar 2015 20:35:25 -0500 Received: from szxga01-in.huawei.com ([58.251.152.64]:41137 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754405AbbCFBfH (ORCPT ); Thu, 5 Mar 2015 20:35:07 -0500 Message-ID: <54F9043D.2060706@huawei.com> Date: Fri, 6 Mar 2015 09:34:53 +0800 From: "Yun Wu (Abel)" User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:11.0) Gecko/20120327 Thunderbird/11.0.1 MIME-Version: 1.0 To: Marc Zyngier CC: "tglx@linutronix.de" , "jason@lakedaemon.net" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" Subject: Re: [PATCH v3 5/5] irqchip: gicv3-its: support safe initialization References: <1425439098-10708-1-git-send-email-wuyun.wu@huawei.com> <1425439098-10708-6-git-send-email-wuyun.wu@huawei.com> <54F8468D.7090902@arm.com> In-Reply-To: <54F8468D.7090902@arm.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.177.24.136] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2015/3/5 20:05, Marc Zyngier wrote: > On 04/03/15 03:18, Yun Wu wrote: >> It's unsafe to change the configurations of an activated ITS directly >> since this will lead to unpredictable results. This patch guarantees >> the ITSes being initialized are quiescent. >> >> Signed-off-by: Yun Wu >> --- >> drivers/irqchip/irq-gic-v3-its.c | 35 +++++++++++++++++++++++++++++++++++ >> 1 file changed, 35 insertions(+) >> >> diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c >> index d13c24e..9e09aa0 100644 >> --- a/drivers/irqchip/irq-gic-v3-its.c >> +++ b/drivers/irqchip/irq-gic-v3-its.c >> @@ -1320,6 +1320,34 @@ static const struct irq_domain_ops its_domain_ops = { >> .deactivate = its_irq_domain_deactivate, >> }; >> >> +static int its_check_quiesced(void __iomem *base) > > Another nitpick: Rather than "its_check_quiesced", how about > "its_force_quiescent" instead? Because this does a lot more than just > checking. Yes, indeed. > >> +{ >> + u32 count = 1000000; /* 1s */ >> + u32 val; >> + >> + val = readl_relaxed(base + GITS_CTLR); >> + if (val & GITS_CTLR_QUIESCENT) >> + return 0; >> + >> + /* Disable the generation of all interrupts to this ITS */ >> + val &= ~GITS_CTLR_ENABLE; >> + writel_relaxed(val, base + GITS_CTLR); >> + >> + /* Poll GITS_CTLR and wait until ITS becomes quiescent */ >> + while (1) { >> + val = readl_relaxed(base + GITS_CTLR); >> + if (val & GITS_CTLR_QUIESCENT) >> + return 0; >> + >> + count--; >> + if (!count) >> + return -EBUSY; >> + >> + cpu_relax(); >> + udelay(1); >> + } >> +} >> + > > I still dislike this repeated pattern, but I don't have a good solution > so far. Me too. > >> static int its_probe(struct device_node *node, struct irq_domain *parent) >> { >> struct resource res; >> @@ -1348,6 +1376,13 @@ static int its_probe(struct device_node *node, struct irq_domain *parent) >> goto out_unmap; >> } >> >> + err = its_check_quiesced(its_base); >> + if (err) { >> + pr_warn("%s: failed to quiesce, giving up\n", >> + node->full_name); >> + goto out_unmap; >> + } >> + >> pr_info("ITS: %s\n", node->full_name); >> >> its = kzalloc(sizeof(*its), GFP_KERNEL); >> -- >> 1.8.0 >> >> >> > > Assuming you fix the above nitpick: > > Acked-by: Marc Zyngier > Thanks, Abel