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Date:   Mon, 11 Feb 2019 16:03:07 +0530
From:   Viresh Kumar <viresh.kumar@linaro.org>
To:     Chen Yu <yu.c.chen@intel.com>
Cc:     "Rafael J. Wysocki" <rjw@rjwysocki.net>,
        Len Brown <lenb@kernel.org>,
        Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
        linux-acpi@vger.kernel.org, linux-pm@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH][RFC] ACPI: add "processor.broadcast_ppc" hook to
 broadcast  _PPC to all online CPUs
Message-ID: <20190211103307.rccddkso3f5s3yko@vireshk-i7>
References: <20190209120232.21582-1-yu.c.chen@intel.com>
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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