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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 1731BC4361A for ; Fri, 4 Dec 2020 07:33:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BC04B22581 for ; Fri, 4 Dec 2020 07:33:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728742AbgLDHdJ (ORCPT ); Fri, 4 Dec 2020 02:33:09 -0500 Received: from szxga05-in.huawei.com ([45.249.212.191]:9103 "EHLO szxga05-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726826AbgLDHdG (ORCPT ); Fri, 4 Dec 2020 02:33:06 -0500 Received: from DGGEMS404-HUB.china.huawei.com (unknown [172.30.72.59]) by szxga05-in.huawei.com (SkyGuard) with ESMTP id 4CnPXh56xczM0M1; Fri, 4 Dec 2020 15:31:48 +0800 (CST) Received: from DESKTOP-5IS4806.china.huawei.com (10.174.187.37) by DGGEMS404-HUB.china.huawei.com (10.3.19.204) with Microsoft SMTP Server id 14.3.487.0; Fri, 4 Dec 2020 15:32:14 +0800 From: Keqian Zhu To: , , , CC: Marc Zyngier , Daniel Lezcano , Thomas Gleixner , Catalin Marinas , Will Deacon , James Morse , Suzuki K Poulose , "Sean Christopherson" , Julien Thierry , Mark Brown , "Andrew Morton" , Alexios Zavras , , Keqian Zhu Subject: [PATCH v3 2/2] clocksource: arm_arch_timer: Correct fault programming of CNTKCTL_EL1.EVNTI Date: Fri, 4 Dec 2020 15:31:26 +0800 Message-ID: <20201204073126.6920-3-zhukeqian1@huawei.com> X-Mailer: git-send-email 2.8.4.windows.1 In-Reply-To: <20201204073126.6920-1-zhukeqian1@huawei.com> References: <20201204073126.6920-1-zhukeqian1@huawei.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.174.187.37] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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") Suggested-by: Marc Zyngier Signed-off-by: Keqian Zhu --- drivers/clocksource/arm_arch_timer.c | 23 ++++++++++++++++------- 1 file changed, 16 insertions(+), 7 deletions(-) diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c index 777d38cb39b0..d0177824c518 100644 --- a/drivers/clocksource/arm_arch_timer.c +++ b/drivers/clocksource/arm_arch_timer.c @@ -822,15 +822,24 @@ static void arch_timer_evtstrm_enable(int divider) static void arch_timer_configure_evtstream(void) { - int evt_stream_div, pos; + int evt_stream_div, lsb; + + /* + * 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; + + /* + * Find the closest power of two to the divisor. If the adjacent bit + * of lsb (last set bit, starts from 0) is set, then we use (lsb + 1). + */ + lsb = fls(evt_stream_div) - 1; + if (lsb > 0 && (evt_stream_div & BIT(lsb - 1))) + lsb++; - /* 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)))) - pos--; /* enable event stream */ - arch_timer_evtstrm_enable(min(pos, 15)); + arch_timer_evtstrm_enable(max(0, min(lsb, 15))); } static void arch_counter_set_user_access(void) -- 2.23.0