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cpufreq: Bring CPUs up even if cpufreq_online() failed 

There is a report that after commit 27622b061e ("cpufreq: Convert
to hotplug state machine"), the normal CPU offline/online cycle
fails on some platforms.

According to the ftrace result, this problem was triggered on
platforms using acpi-cpufreq as the default cpufreq driver,
and due to the lack of some ACPI freq method (eg. _PCT),
cpufreq_online() failed and returned a negative value, so the CPU
hotplug state machine rolled back the CPU online process.  Actually,
from the user's perspective, the failure of cpufreq_online() should
not prevent that CPU from being brought up, although cpufreq might
not work on that CPU.

BTW, during system startup cpufreq_online() is not invoked via CPU
online but by the cpufreq device creation process, so the APs can be
brought up even though cpufreq_online() fails in that stage.

This patch ignores the return value of cpufreq_online/offline() and
lets the cpufreq framework deal with the failure.  cpufreq_online()
itself will do a proper rollback in that case and if _PCT is missing,
the ACPI cpufreq driver will print a warning if the corresponding
debug options have been enabled.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=194581
Fixes: 27622b061e ("cpufreq: Convert to hotplug state machine")
Reported-and-tested-by: Tomasz Maciej Nowak <tmn505@gmail.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: 4.9+ <stable@vger.kernel.org> # 4.9+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Chen Yu 2017-04-09 13:45:16 +08:00 committed by Rafael J. Wysocki
parent 39da7c509a
commit c4a3fa261b
1 changed files with 16 additions and 2 deletions
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18
drivers/cpufreq/cpufreq.c
View File

@ -2398,6 +2398,20 @@ EXPORT_SYMBOL_GPL(cpufreq_boost_enabled);
*********************************************************************/
static enum cpuhp_state hp_online;
static int cpuhp_cpufreq_online(unsigned int cpu)
{
cpufreq_online(cpu);
return 0;
}
static int cpuhp_cpufreq_offline(unsigned int cpu)
{
cpufreq_offline(cpu);
return 0;
}
/**
* cpufreq_register_driver - register a CPU Frequency driver
* @driver_data: A struct cpufreq_driver containing the values#
@ -2460,8 +2474,8 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data)
}
ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "cpufreq:online",
cpufreq_online,
cpufreq_offline);
cpuhp_cpufreq_online,
cpuhp_cpufreq_offline);
if (ret < 0)
goto err_if_unreg;
hp_online = ret;