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=-10.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 87411C433E5 for ; Tue, 28 Jul 2020 10:18:21 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 57DE720714 for ; Tue, 28 Jul 2020 10:18:21 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="GwP/+zpz"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="VBdHKzom" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 57DE720714 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Type: Content-Transfer-Encoding:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:Message-ID:References:In-Reply-To:Subject:To:From: Date:MIME-Version:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=Qhs+5qjlCOIQxL+3dFFNGdOqMG1cCJCbLalk1pvCQQo=; b=GwP/+zpzsYg8Q9dYFTaMw2fxg Fp8/fe5MGBjVRvZqID8pOwI/9jnCIP3KQsdfM37TAmQojMZQ4C67D04L8b9tO8Qml8heilxcXMxAa 09c8khX8bL8muw2dkv4mF2s72a7PQLWDug/zUa8l2L6rntR4ypGqVVPxcevytB5L4p+pcLeCtsGEv /0G2GfTNggYKTFS0KXXu2anhnvV/xuN/0q1sRFBjJgcsdz2QsfEj+fDiAT0h6nYX+nF4cysQw38IN MyTN0YfEWXD450G4bJQC5TLgB1V6ZV4XXrCkdaf6SQ+hOXx2mq9jjR1kPS85NhDLRGlIOii4990iD +8dQ7hWew==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1k0MfN-0003gG-Hu; Tue, 28 Jul 2020 10:17:01 +0000 Received: from mail.kernel.org ([198.145.29.99]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1k0MfC-0003cZ-Jk for linux-arm-kernel@lists.infradead.org; Tue, 28 Jul 2020 10:16:55 +0000 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 9BFB320714; Tue, 28 Jul 2020 10:16:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595931409; bh=ZfZF4pLvNemxD3En2Fwag4OkbrDfzKVU9SSSrL6fd/A=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=VBdHKzomeWjgG1TMubp9tgrJfSfvIiWmv/K4FkXE5Rs7AJCr+6dTw7JhR+SJdMQYt fPlyE+EJ3CP6EqlEzoY0Ft3LE0pMPFyKPhAVwGK3Qo4iqhoODr1mWy8T3OvnA7FuDq 4MT7WpcnF3emS2LhtbRxOesdw6RmcyTlTn3bQdJM= Received: from disco-boy.misterjones.org ([51.254.78.96] helo=www.loen.fr) by disco-boy.misterjones.org with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1k0Mf9-00FcMr-Ug; Tue, 28 Jul 2020 11:16:48 +0100 MIME-Version: 1.0 Date: Tue, 28 Jul 2020 11:16:47 +0100 From: Marc Zyngier To: Keqian Zhu Subject: Re: [RESEND PATCH] drivers: arm arch timer: Correct fault programming of CNTKCTL_EL1.EVNTI In-Reply-To: <20200717092104.15428-1-zhukeqian1@huawei.com> References: <20200717092104.15428-1-zhukeqian1@huawei.com> User-Agent: Roundcube Webmail/1.4.5 Message-ID: <3a95ec8ce3e34d86c09f9b1b4f17d0ad@kernel.org> 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, 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 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200728_061650_926627_62052F2E X-CRM114-Status: GOOD ( 25.20 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kvm@vger.kernel.org, Suzuki K Poulose , Catalin Marinas , linux-kernel@vger.kernel.org, James Morse , wanghaibin.wang@huawei.com, Will Deacon , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2020-07-17 10:21, Keqian Zhu wrote: > ARM virtual counter supports event stream. It can only trigger an event > when the trigger bit of CNTVCT_EL0 changes from 0 to 1 (or from 1 to > 0), > so the actual period of event stream is 2 ^ (cntkctl_evnti + 1). For > example, when the trigger bit is 0, then it triggers an event for every > two cycles. > > Signed-off-by: Keqian Zhu > --- > drivers/clocksource/arm_arch_timer.c | 17 ++++++++++++++--- > 1 file changed, 14 insertions(+), 3 deletions(-) > > diff --git a/drivers/clocksource/arm_arch_timer.c > b/drivers/clocksource/arm_arch_timer.c > index ecf7b7db2d05..06d99a4b1b9b 100644 > --- a/drivers/clocksource/arm_arch_timer.c > +++ b/drivers/clocksource/arm_arch_timer.c > @@ -799,10 +799,20 @@ static void __arch_timer_setup(unsigned type, > static void arch_timer_evtstrm_enable(int divider) > { > u32 cntkctl = arch_timer_get_cntkctl(); > + int cntkctl_evnti; > + > + /* > + * Note that it can only trigger an event when the trigger bit > + * of CNTVCT_EL0 changes from 1 to 0 (or from 0 to 1), so the > + * actual period of event stream is 2 ^ (cntkctl_evnti + 1). > + */ > + cntkctl_evnti = divider - 1; > + cntkctl_evnti = min(cntkctl_evnti, 15); > + cntkctl_evnti = max(cntkctl_evnti, 0); > > cntkctl &= ~ARCH_TIMER_EVT_TRIGGER_MASK; > /* Set the divider and enable virtual event stream */ > - cntkctl |= (divider << ARCH_TIMER_EVT_TRIGGER_SHIFT) > + cntkctl |= (cntkctl_evnti << ARCH_TIMER_EVT_TRIGGER_SHIFT) > | ARCH_TIMER_VIRT_EVT_EN; > arch_timer_set_cntkctl(cntkctl); > arch_timer_set_evtstrm_feature(); > @@ -816,10 +826,11 @@ static void arch_timer_configure_evtstream(void) > /* Find the closest power of two to the divisor */ > evt_stream_div = arch_timer_rate / ARCH_TIMER_EVT_STREAM_FREQ; > 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--; > + > /* enable event stream */ > - arch_timer_evtstrm_enable(min(pos, 15)); > + arch_timer_evtstrm_enable(pos); > } > > static void arch_counter_set_user_access(void) This looks like a very convoluted fix. If the problem you are trying to fix is that the event frequency is at most half of that of the counter, why isn't the patch below the most obvious fix? Thanks, M. diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c index 6c3e84180146..0a65414b781f 100644 --- a/drivers/clocksource/arm_arch_timer.c +++ b/drivers/clocksource/arm_arch_timer.c @@ -824,8 +824,12 @@ 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)))) pos--; -- Jazz is not dead. It just smells funny... _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel