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SubjectRe: [PATCH 2/2] cpufreq: intel_pstate: enable HWP after resumed
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On Monday, January 29, 2018 3:27:57 AM CET Yu Chen wrote:
> When maxcpus=1 is appended the BP is responsible
> for re-enabling the HWP - because currently only
> the APs invoke intel_pstate_hwp_enable() during
> their online process - which might put the system
> into unstable state after resume.
>
> Fix this by enabling the HWP explicitly on BP during
> resume.
>
> Reported-by: Doug Smythies <dsmythies@telus.net>
> Suggested-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
> Signed-off-by: Yu Chen <yu.c.chen@intel.com>
> ---
> drivers/cpufreq/intel_pstate.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
> index 93a0e88bef76..89f637e8439c 100644
> --- a/drivers/cpufreq/intel_pstate.c
> +++ b/drivers/cpufreq/intel_pstate.c
> @@ -779,6 +779,8 @@ static int intel_pstate_hwp_save_state(struct cpufreq_policy *policy)
> return 0;
> }
>
> +static void intel_pstate_hwp_enable(struct cpudata *cpudata);
> +
> static int intel_pstate_resume(struct cpufreq_policy *policy)
> {
> if (!hwp_active)
> @@ -786,6 +788,8 @@ static int intel_pstate_resume(struct cpufreq_policy *policy)
>
> mutex_lock(&intel_pstate_limits_lock);
>
> + if (!policy->cpu)
> + intel_pstate_hwp_enable(all_cpu_data[policy->cpu]);
> all_cpu_data[policy->cpu]->epp_policy = 0;
> intel_pstate_hwp_set(policy->cpu);
>
>

I've applied this one (with minor modifications) as a temporary measure, but
it is based on the CPU0=BP assumption which may not be the case.

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