There is a report that after commit 27622b061eb4 ("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: 27622b061eb4 ("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>

* pm-cpufreq-fixes:
  cpufreq: Fix creation of symbolic links to policy directories

* pm-cpuidle-fixes:
  cpuidle: powernv: Pass correct drv->cpumask for registration

The cpufreq core only tries to create symbolic links from CPU
directories in sysfs to policy directories in cpufreq_add_dev(),
either when a given CPU is registered or when the cpufreq driver
is registered, whichever happens first.  That is not sufficient,
however, because cpufreq_add_dev() may be called for an offline CPU
whose policy object has not been created yet and, quite obviously,
the symbolic cannot be added in that case.

Fix that by making cpufreq_online() attempt to add symbolic links to
policy objects for the CPUs in the related_cpus mask of every new
policy object created by it.

The cpufreq_driver_lock locking around the for_each_cpu() loop
in cpufreq_online() is dropped, because it is not necessary and the
code is somewhat simpler without it.  Moreover, failures to create
a symbolic link will not be regarded as hard errors any more and
the CPUs without those links will not be taken offline automatically,
but that should not be problematic in practice.

Reported-and-tested-by: Prashanth Prakash <pprakash@codeaurora.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: 4.9+ <stable@vger.kernel.org> # 4.9+

* pm-cpufreq-fixes:
  cpufreq: Restore policy min/max limits on CPU online

* pm-cpufreq-sched-fixes:
  cpufreq: schedutil: Fix per-CPU structure initialization in sugov_start()

* intel_pstate-fixes:
  cpufreq: intel_pstate: Fix policy data management in passive mode
  cpufreq: intel_pstate: One set of global limits in active mode

On CPU online the cpufreq core restores the previous governor (or
the previous "policy" setting for ->setpolicy drivers), but it does
not restore the min/max limits at the same time, which is confusing,
inconsistent and real pain for users who set the limits and then
suspend/resume the system (using full suspend), in which case the
limits are reset on all CPUs except for the boot one.

Fix this by making cpufreq_online() restore the limits when an inactive
policy is brought online.

The commit log and patch are inspired from Rafael's earlier work.

Reported-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: 4.3+ <stable@vger.kernel.org> # 4.3+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

The policy->cpuinfo.max_freq and policy->max updates in
intel_cpufreq_turbo_update() are excessive as they are done for no
good reason and may lead to problems in principle, so they should be
dropped.  However, after dropping them intel_cpufreq_turbo_update()
becomes almost entirely pointless, because the check made by it is
made again down the road in intel_pstate_prepare_request().  The
only thing in it that still needs to be done is the call to
update_turbo_state(), so drop intel_cpufreq_turbo_update() altogether
and make its callers invoke update_turbo_state() directly instead of
it.

In addition to that, fix intel_cpufreq_verify_policy() so that it
checks global.no_turbo in addition to global.turbo_disabled when
updating policy->cpuinfo.max_freq to make it consistent with
intel_pstate_verify_policy().

Fixes: 001c76f05b01 (cpufreq: intel_pstate: Generic governors support)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

In the active mode intel_pstate currently uses two sets of global
limits, each associated with one of the possible scaling_governor
settings in that mode: "powersave" or "performance".

The driver switches over from one of those sets to the other
depending on the scaling_governor setting for the last CPU whose
per-policy cpufreq interface in sysfs was last used to change
parameters exposed in there.  That obviously leads to no end of
issues when the scaling_governor settings differ between CPUs.

The most recent issue was introduced by commit a240c4aa5d0f (cpufreq:
intel_pstate: Do not reinit performance limits in ->setpolicy)
that eliminated the reinitialization of "performance" limits in
intel_pstate_set_policy() preventing the max limit from being set
to anything below 100, among other things.

Namely, an undesirable side effect of commit a240c4aa5d0f is that
now, after setting scaling_governor to "performance" in the active
mode, the per-policy limits for the CPU in question go to the highest
level and stay there even when it is switched back to "powersave"
later.

As it turns out, some distributions set scaling_governor to
"performance" temporarily for all CPUs to speed-up system
initialization, so that change causes them to misbehave later.

To fix that, get rid of the performance/powersave global limits
split and use just one set of global limits for everything.

From the user's persepctive, after this modification, when
scaling_governor is switched from "performance" to "powersave"
or the other way around on one CPU, the limits settings (ie. the
global max/min_perf_pct and per-policy scaling_max/min_freq for
any CPUs) will not change.  Still, switching from "performance"
to "powersave" or the other way around changes the way in which
P-states are selected and in particular "performance" causes the
driver to always request the highest P-state it is allowed to ask
for for the given CPU.

Fixes: a240c4aa5d0f (cpufreq: intel_pstate: Do not reinit performance limits in ->setpolicy)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

* pm-cpufreq-fixes:
  cpufreq: Fix and clean up show_cpuinfo_cur_freq()

* intel_pstate-fixes:
  cpufreq: intel_pstate: Avoid percentages in limits-related computations
  cpufreq: intel_pstate: Correct frequency setting in the HWP mode
  cpufreq: intel_pstate: Update pid_params.sample_rate_ns in pid_param_set()

There is a missing newline in show_cpuinfo_cur_freq(), so add it,
but while at it clean that function up somewhat too.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: All applicable <stable@vger.kernel.org>

Currently, intel_pstate_update_perf_limits() first converts the
policy minimum and maximum limits into percentages of the maximum
turbo frequency (rounding up to an integer) and then converts these
percentages to fractions (by using fixed-point arithmetic to divide
them by 100).

That introduces a rounding error unnecessarily, because the fractions
can be obtained by carrying out fixed-point divisions directly on the
input numbers.

Rework the computations in intel_pstate_hwp_set() to use fractions
instead of percentages (and drop redundant local variables from
there) and modify intel_pstate_update_perf_limits() to compute the
fractions directly and percentages out of them.

While at it, introduce percent_ext_fp() for converting percentages
to fractions (with extended number of fraction bits) and use it in
the computations.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>