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

Viresh Kumar
2019-02-11T10:33:07Z

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 &&

Why do have this check for policy->max here ?

> + 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)
> --
> 2.17.1

--
viresh