From patchwork Thu May 21 14:07:23 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Serge Semin X-Patchwork-Id: 11563041 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 CDD6914B7 for ; Thu, 21 May 2020 14:09:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BF3B7208A9 for ; Thu, 21 May 2020 14:09:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729944AbgEUOJG (ORCPT ); Thu, 21 May 2020 10:09:06 -0400 Received: from mail.baikalelectronics.com ([87.245.175.226]:38616 "EHLO mail.baikalelectronics.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729926AbgEUOJD (ORCPT ); Thu, 21 May 2020 10:09:03 -0400 Received: from localhost (unknown [127.0.0.1]) by mail.baikalelectronics.ru (Postfix) with ESMTP id 777FD8029EC9; Thu, 21 May 2020 14:09:00 +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 DztnQ5E9A5B6; Thu, 21 May 2020 17:08:59 +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 , , Jiaxun Yang , Alexander Lobakin , Huacai Chen , Vincenzo Frascino , Thomas Gleixner , , Subject: [PATCH v4 12/13] mips: csrc-r4k: Mark R4K timer as unstable if CPU freq changes Date: Thu, 21 May 2020 17:07:23 +0300 Message-ID: <20200521140725.29571-13-Sergey.Semin@baikalelectronics.ru> In-Reply-To: <20200521140725.29571-1-Sergey.Semin@baikalelectronics.ru> References: <20200521140725.29571-1-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 --- 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 2747b1b2d435..f347312ecd74 100644 --- a/arch/mips/Kconfig +++ b/arch/mips/Kconfig @@ -1108,6 +1108,7 @@ 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)