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cpufreq: intel_pstate: Fix invalid EPB setting

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The max value of EPB can only be 0x0F. Attempting to set more than that
triggers an "unchecked MSR access error" warning which happens in
intel_pstate_hwp_force_min_perf() called via cpufreq stop_cpu().

However, it is not even necessary to touch the EPB from intel_pstate,
because it is restored on every CPU online by the intel_epb.c code,
so let that code do the right thing and drop the redundant (and
incorrect) EPB update from intel_pstate.

Fixes: af3b7379e2 ("cpufreq: intel_pstate: Force HWP min perf before offline")
Reported-by: Qian Cai <cai@lca.pw>
Cc: 5.2+ <stable@vger.kernel.org> # 5.2+
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
[ rjw: Changelog ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Srinivas Pandruvada 2019-10-31 12:26:20 -07:00 committed by Rafael J. Wysocki
parent a99d8080aa
commit c31432fa7f
1 changed files with 1 additions and 3 deletions
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4
drivers/cpufreq/intel_pstate.c
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@ -847,11 +847,9 @@ static void intel_pstate_hwp_force_min_perf(int cpu)
value |= HWP_MAX_PERF(min_perf);
value |= HWP_MIN_PERF(min_perf);
/* Set EPP/EPB to min */
/* Set EPP to min */
if (boot_cpu_has(X86_FEATURE_HWP_EPP))
value |= HWP_ENERGY_PERF_PREFERENCE(HWP_EPP_POWERSAVE);
else
intel_pstate_set_epb(cpu, HWP_EPP_BALANCE_POWERSAVE);
wrmsrl_on_cpu(cpu, MSR_HWP_REQUEST, value);
}