From patchwork Thu May 21 00:34:42 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Serge Semin X-Patchwork-Id: 11561847 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id BDEF713B1 for ; Thu, 21 May 2020 00:35:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B04B22078C for ; Thu, 21 May 2020 00:35:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727867AbgEUAfp (ORCPT ); Wed, 20 May 2020 20:35:45 -0400 Received: from mail.baikalelectronics.com ([87.245.175.226]:33264 "EHLO mail.baikalelectronics.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727785AbgEUAff (ORCPT ); Wed, 20 May 2020 20:35:35 -0400 Received: from localhost (unknown [127.0.0.1]) by mail.baikalelectronics.ru (Postfix) with ESMTP id E6A5E8029EB7; Thu, 21 May 2020 00:35:32 +0000 (UTC) X-Virus-Scanned: amavisd-new at baikalelectronics.ru Received: from mail.baikalelectronics.ru ([127.0.0.1]) by localhost (mail.baikalelectronics.ru [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 282dDLsDfqmV; Thu, 21 May 2020 03:35:32 +0300 (MSK) From: Serge Semin To: Thomas Bogendoerfer CC: Serge Semin , Serge Semin , Alexey Malahov , Paul Burton , Ralf Baechle , Greg Kroah-Hartman , Arnd Bergmann , Rob Herring , , Thomas Bogendoerfer , Jiaxun Yang , Huacai Chen , Alexander Lobakin , Thomas Gleixner , Vincenzo Frascino , , Subject: [PATCH v3 13/14] mips: csrc-r4k: Mark R4K timer as unstable if CPU freq changes Date: Thu, 21 May 2020 03:34:42 +0300 Message-ID: <20200521003443.11385-14-Sergey.Semin@baikalelectronics.ru> In-Reply-To: <20200521003443.11385-1-Sergey.Semin@baikalelectronics.ru> References: <20200521003443.11385-1-Sergey.Semin@baikalelectronics.ru> MIME-Version: 1.0 X-ClientProxiedBy: MAIL.baikal.int (192.168.51.25) To mail (192.168.51.25) Sender: linux-mips-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org Commit 07d69579e7fe ("MIPS: Don't register r4k sched clock when CPUFREQ enabled") disabled the r4k-clock usage for scheduler ticks counting due to the scheduler being non-tolerant for unstable clocks sources. For the same reason the clock should be used in the system clocksource framework with care. As soon as CPU frequency changes the clocksource framework should be notified about this by marking the R4K timer being unstable (which it really is, since the ticks rate has been changed synchronously with the CPU frequency). Signed-off-by: Serge Semin Cc: Alexey Malahov Cc: Thomas Bogendoerfer Cc: Paul Burton Cc: Ralf Baechle Cc: Greg Kroah-Hartman Cc: Arnd Bergmann Cc: Rob Herring Cc: devicetree@vger.kernel.org --- Changelog v3: - Mark clocksource as unstable instead of lowering its rating. --- arch/mips/Kconfig | 1 + arch/mips/kernel/csrc-r4k.c | 40 +++++++++++++++++++++++++++++++++++++ 2 files changed, 41 insertions(+) diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig index b0eff203fbd8..c2911864fee1 100644 --- a/arch/mips/Kconfig +++ b/arch/mips/Kconfig @@ -1154,6 +1154,7 @@ config CSRC_IOASIC bool config CSRC_R4K + select CLOCKSOURCE_WATCHDOG if CPU_FREQ bool config CSRC_SB1250 diff --git a/arch/mips/kernel/csrc-r4k.c b/arch/mips/kernel/csrc-r4k.c index 437dda64fd7a..edc4afc080fa 100644 --- a/arch/mips/kernel/csrc-r4k.c +++ b/arch/mips/kernel/csrc-r4k.c @@ -6,6 +6,7 @@ * Copyright (C) 2007 by Ralf Baechle */ #include +#include #include #include @@ -65,6 +66,45 @@ static bool rdhwr_count_usable(void) return false; } +#ifdef CONFIG_CPU_FREQ + +static bool __read_mostly r4k_clock_unstable; + +static void r4k_clocksource_unstable(char *reason) +{ + if (r4k_clock_unstable) + return; + + r4k_clock_unstable = true; + + pr_info("R4K timer is unstable due to %s\n", reason); + + clocksource_mark_unstable(&clocksource_mips); +} + +static int r4k_cpufreq_callback(struct notifier_block *nb, + unsigned long val, void *data) +{ + if (val == CPUFREQ_POSTCHANGE) + r4k_clocksource_unstable("CPU frequency change"); + + return 0; +} + +static struct notifier_block r4k_cpufreq_notifier = { + .notifier_call = r4k_cpufreq_callback, +}; + +static int __init r4k_register_cpufreq_notifier(void) +{ + return cpufreq_register_notifier(&r4k_cpufreq_notifier, + CPUFREQ_TRANSITION_NOTIFIER); + +} +core_initcall(r4k_register_cpufreq_notifier); + +#endif /* !CONFIG_CPU_FREQ */ + int __init init_r4k_clocksource(void) { if (!cpu_has_counter || !mips_hpt_frequency)