Re: [PATCH][RFC] ACPI: add "processor.broadcast_ppc" hook to broadcast _PPC to all online CPUs

Rafael J. Wysocki
2019-02-11T10:20:51Z

On Mon, Feb 11, 2019 at 10:16 AM Viresh Kumar <viresh.kumar@linaro.org> wrote:
>
> On 09-02-19, 20:02, Chen Yu wrote:
> > On Dell Inc. XPS13 9333, the BIOS changes the value of
> > MSR_IA32_MISC_ENABLE_TURBO_DISABLE at runtime (e.g., when
> > the power source changes), the maximum frequency of the
> > CPU is not updated accordingly. This is due to the policy's
> > cpuinfo.max is not updated when _PPC notifier fires.
> >
> > Fix this problem by updating the policy's cpuinfo.max
> > and broadcast the _PPC notifier to all online CPUs.
> >
> > Link: https://bugzilla.kernel.org/show_bug.cgi?id=200759
> > Reported-and-tested-by: Gabriele Mazzotta <gabriele.mzt@gmail.com>
> > Originally-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
> > Signed-off-by: Chen Yu <yu.c.chen@intel.com>
> > ---
> > drivers/acpi/processor_perflib.c | 16 ++++++++++++++--
> > drivers/cpufreq/cpufreq.c | 2 ++
> > drivers/cpufreq/intel_pstate.c | 15 ++++++++++++++-
> > 3 files changed, 30 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/acpi/processor_perflib.c b/drivers/acpi/processor_perflib.c
> > index a303fd0e108c..737dbf5aa7f7 100644
> > --- a/drivers/acpi/processor_perflib.c
> > +++ b/drivers/acpi/processor_perflib.c
> > @@ -63,6 +63,10 @@ module_param(ignore_ppc, int, 0644);
> > MODULE_PARM_DESC(ignore_ppc, "If the frequency of your machine gets wrongly" \
> > "limited by BIOS, this should help");
> >
> > +static int broadcast_ppc;
> > +module_param(broadcast_ppc, int, 0644);
> > +MODULE_PARM_DESC(broadcast_ppc, "Broadcast the ppc to all online CPUs");
> > +
> > #define PPC_REGISTERED 1
> > #define PPC_IN_USE 2
> >
> > @@ -180,8 +184,16 @@ void acpi_processor_ppc_has_changed(struct acpi_processor *pr, int event_flag)
> > else
> > acpi_processor_ppc_ost(pr->handle, 0);
> > }
> > - if (ret >= 0)
> > - cpufreq_update_policy(pr->id);
> > + if (ret >= 0) {
> > + if (broadcast_ppc) {
> > + int cpu;
> > +
> > + for_each_possible_cpu(cpu)
> > + cpufreq_update_policy(cpu);
> > + } else {
> > + cpufreq_update_policy(pr->id);
> > + }
> > + }
> > }
> >
> > int acpi_processor_get_bios_limit(int cpu, unsigned int *limit)
> > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> > index e35a886e00bc..95e08816b512 100644
> > --- a/drivers/cpufreq/cpufreq.c
> > +++ b/drivers/cpufreq/cpufreq.c
> > @@ -2237,6 +2237,8 @@ static int cpufreq_set_policy(struct cpufreq_policy *policy,
> >
> > policy->min = new_policy->min;
> > policy->max = new_policy->max;
> > + policy->cpuinfo.max_freq = new_policy->cpuinfo.max_freq;
> > + policy->cpuinfo.min_freq = new_policy->cpuinfo.min_freq;
> > trace_cpu_frequency_limits(policy);
> >
> > policy->cached_target_freq = UINT_MAX;
> > diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
> > index dd66decf2087..e1881313c396 100644
> > --- a/drivers/cpufreq/intel_pstate.c
> > +++ b/drivers/cpufreq/intel_pstate.c
> > @@ -2081,11 +2081,24 @@ static void intel_pstate_adjust_policy_max(struct cpufreq_policy *policy,
> >
> > static int intel_pstate_verify_policy(struct cpufreq_policy *policy)
> > {
> > + int max_freq;
> > struct cpudata *cpu = all_cpu_data[policy->cpu];
> >
> > update_turbo_state();
> > + max_freq = intel_pstate_get_max_freq(cpu);
> > +
> > + if (acpi_ppc && policy->max == policy->cpuinfo.max_freq &&
> > + max_freq != policy->cpuinfo.max_freq) {
> > + /*
> > + * System was not running under any constraints, but the
> > + * current max possible frequency is changed. So reset
> > + * policy limits.
> > + */
> > + policy->cpuinfo.max_freq = policy->max = max_freq;
> > + }
> > +
> > cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
> > - intel_pstate_get_max_freq(cpu));
> > + max_freq);
> >
> > if (policy->policy != CPUFREQ_POLICY_POWERSAVE &&
> > policy->policy != CPUFREQ_POLICY_PERFORMANCE)
>
> By TURBO I believe this is about boost-frequencies and you should use
> that infrastructure to make it work, isn't it ?

I guess you mean the the "boost" attribute in the core, but that's not
applicable to intel_pstate.