From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.0 required=3.0 tests=BAYES_00,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4FBE7C433FE for ; Thu, 3 Dec 2020 14:58:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DDC55206D6 for ; Thu, 3 Dec 2020 14:58:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728340AbgLCO6F (ORCPT ); Thu, 3 Dec 2020 09:58:05 -0500 Received: from mail.kernel.org ([198.145.29.99]:51976 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725903AbgLCO6F (ORCPT ); Thu, 3 Dec 2020 09:58:05 -0500 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id CA2E4206D6; Thu, 3 Dec 2020 14:57:23 +0000 (UTC) Received: from disco-boy.misterjones.org ([51.254.78.96] helo=www.loen.fr) by disco-boy.misterjones.org with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.94) (envelope-from ) id 1kkq2r-00FhLT-G9; Thu, 03 Dec 2020 14:57:21 +0000 MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Thu, 03 Dec 2020 14:57:21 +0000 From: Marc Zyngier To: Keqian Zhu Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, Steven Price , Andrew Jones , Catalin Marinas , Will Deacon , James Morse , Suzuki K Poulose , wanghaibin.wang@huawei.com Subject: Re: [PATCH v2 2/2] clocksource: arm_arch_timer: Correct fault programming of CNTKCTL_EL1.EVNTI In-Reply-To: <20200818032814.15968-3-zhukeqian1@huawei.com> References: <20200818032814.15968-1-zhukeqian1@huawei.com> <20200818032814.15968-3-zhukeqian1@huawei.com> User-Agent: Roundcube Webmail/1.4.9 Message-ID: X-Sender: maz@kernel.org X-SA-Exim-Connect-IP: 51.254.78.96 X-SA-Exim-Rcpt-To: zhukeqian1@huawei.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, steven.price@arm.com, drjones@redhat.com, catalin.marinas@arm.com, will@kernel.org, james.morse@arm.com, suzuki.poulose@arm.com, wanghaibin.wang@huawei.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020-08-18 04:28, Keqian Zhu wrote: > ARM virtual counter supports event stream, it can only trigger an event > when the trigger bit (the value of CNTKCTL_EL1.EVNTI) of CNTVCT_EL0 > changes, > so the actual period of event stream is 2^(cntkctl_evnti + 1). For > example, > when the trigger bit is 0, then virtual counter trigger an event for > every > two cycles. > > Fixes: 037f637767a8 ("drivers: clocksource: add support for > ARM architected timer event stream") Fixes: tags should on a single line. > Suggested-by: Marc Zyngier > Signed-off-by: Keqian Zhu > --- > drivers/clocksource/arm_arch_timer.c | 10 +++++++--- > 1 file changed, 7 insertions(+), 3 deletions(-) > > diff --git a/drivers/clocksource/arm_arch_timer.c > b/drivers/clocksource/arm_arch_timer.c > index 777d38c..e3b2ee0 100644 > --- a/drivers/clocksource/arm_arch_timer.c > +++ b/drivers/clocksource/arm_arch_timer.c > @@ -824,10 +824,14 @@ static void arch_timer_configure_evtstream(void) > { > int evt_stream_div, pos; > > - /* Find the closest power of two to the divisor */ > - evt_stream_div = arch_timer_rate / ARCH_TIMER_EVT_STREAM_FREQ; > + /* > + * Find the closest power of two to the divisor. As the event > + * stream can at most be generated at half the frequency of the > + * counter, use half the frequency when computing the divider. > + */ > + evt_stream_div = arch_timer_rate / ARCH_TIMER_EVT_STREAM_FREQ / 2; > pos = fls(evt_stream_div); > - if (pos > 1 && !(evt_stream_div & (1 << (pos - 2)))) > + if ((pos == 1) || (pos > 1 && !(evt_stream_div & (1 << (pos - 2))))) > pos--; You don't explain why you are special-casing pos == 1. > /* enable event stream */ > arch_timer_evtstrm_enable(min(pos, 15)); Also, please Cc the subsystem maintainers: CLOCKSOURCE, CLOCKEVENT DRIVERS M: Daniel Lezcano M: Thomas Gleixner L: linux-kernel@vger.kernel.org S: Supported T: git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git timers/core F: Documentation/devicetree/bindings/timer/ F: drivers/clocksource/ Thanks, M. -- Jazz is not dead. It just smells funny...