mips: csrc-r4k: Mark R4K timer as unstable if CPU freq changes (38586428) · Commits · 戴 / test

Commit ("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 <Sergey.Semin@baikalelectronics.ru> Cc: Alexey Malahov <Alexey.Malahov@baikalelectronics.ru> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Paul Burton <paulburton@kernel.org> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Rob Herring <robh+dt@kernel.org> Cc: devicetree@vger.kernel.org Signed-off-by:

Thomas Bogendoerfer <tsbogend@alpha.franken.de>

arch/mips/Kconfig

+1 −0

Original line number	Diff line number	Diff line
		@@ -1108,6 +1108,7 @@ config CSRC_IOASIC
		bool

		config CSRC_R4K
		select CLOCKSOURCE_WATCHDOG if CPU_FREQ
		bool

		config CSRC_SB1250

arch/mips/kernel/csrc-r4k.c

+40 −0

Original line number	Diff line number	Diff line
		@@ -6,6 +6,7 @@
		* Copyright (C) 2007 by Ralf Baechle
		*/
		#include <linux/clocksource.h>
		#include <linux/cpufreq.h>
		#include <linux/init.h>
		#include <linux/sched_clock.h>

		@@ -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)

Admin message