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

Chen Yu
2019-02-09T12:02:32Z

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)
--
2.17.1