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Subject[PATCH][v3] cpufreq: intel_pstate: Get percpu max freq via HWP MSR register if available
Date
Currently when turbo is disabled(either by BIOS or by the user), the
intel_pstate driver reads the max non-turbo frequency from the package-wide
MSR_PLATFORM_INFO(0xce) register. However on asymmetric platforms it is
possible in theory that small and big core with HWP enabled might have
different max non-turbo cpu frequency, because the MSR_HWP_CAPABILITIES
is percpu scope according to Intel Software Developer Manual.

The turbo max freq is already percpu basis in current code, thus make
similar change to the max non-turbo frequency as well.

Reported-by: Wendy Wang <wendy.wang@intel.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
---
v2: Per Srinivas' suggestion, avoid duplicated assignment of max_pstate.
v3: Per Rafael's suggestion, do not add new argument in intel_pstate_get_hwp_max()
to avoid redundant local vars.
Per Srinivas' suggestion, refined the commit log to reflect the 'non-turbo'
max frequency.
--
drivers/cpufreq/intel_pstate.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index eaf32ef7a030..99e180f644c3 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -1724,11 +1724,9 @@ static void intel_pstate_max_within_limits(struct cpudata *cpu)
static void intel_pstate_get_cpu_pstates(struct cpudata *cpu)
{
cpu->pstate.min_pstate = pstate_funcs.get_min();
- cpu->pstate.max_pstate = pstate_funcs.get_max();
cpu->pstate.max_pstate_physical = pstate_funcs.get_max_physical();
cpu->pstate.turbo_pstate = pstate_funcs.get_turbo();
cpu->pstate.scaling = pstate_funcs.get_scaling();
- cpu->pstate.max_freq = cpu->pstate.max_pstate * cpu->pstate.scaling;

if (hwp_active && !hwp_mode_bdw) {
unsigned int phy_max, current_max;
@@ -1736,9 +1734,12 @@ static void intel_pstate_get_cpu_pstates(struct cpudata *cpu)
intel_pstate_get_hwp_max(cpu, &phy_max, &current_max);
cpu->pstate.turbo_freq = phy_max * cpu->pstate.scaling;
cpu->pstate.turbo_pstate = phy_max;
+ cpu->pstate.max_pstate = HWP_GUARANTEED_PERF(READ_ONCE(cpu->hwp_cap_cached));
} else {
cpu->pstate.turbo_freq = cpu->pstate.turbo_pstate * cpu->pstate.scaling;
+ cpu->pstate.max_pstate = pstate_funcs.get_max();
}
+ cpu->pstate.max_freq = cpu->pstate.max_pstate * cpu->pstate.scaling;

if (pstate_funcs.get_aperf_mperf_shift)
cpu->aperf_mperf_shift = pstate_funcs.get_aperf_mperf_shift();
--
2.17.1
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