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- From a6e9d2e9ec1a81ff2b45a986bc320f28dc155f1d Mon Sep 17 00:00:00 2001
- From: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
- Date: Thu, 18 Nov 2021 21:18:01 -0800
- Subject: [PATCH 4/6] cpufreq: intel_pstate: ITMT support for overclocked
- system
- On systems with overclocking enabled, CPPC Highest Performance can be
- hard coded to 0xff. In this case even if we have cores with different
- highest performance, ITMT can't be enabled as the current implementation
- depends on CPPC Highest Performance.
- On such systems we can use MSR_HWP_CAPABILITIES maximum performance field
- when CPPC.Highest Performance is 0xff.
- Due to legacy reasons, we can't solely depend on MSR_HWP_CAPABILITIES as
- in some older systems CPPC Highest Performance is the only way to identify
- different performing cores.
- Reported-by: Michael Larabel <Michael@MichaelLarabel.com>
- Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
- ---
- drivers/cpufreq/intel_pstate.c | 10 ++++++++++
- 1 file changed, 10 insertions(+)
- diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
- index e15c3bc17a55..8a2c6b58b652 100644
- --- a/drivers/cpufreq/intel_pstate.c
- +++ b/drivers/cpufreq/intel_pstate.c
- @@ -335,6 +335,8 @@ static void intel_pstste_sched_itmt_work_fn(struct work_struct *work)
-
- static DECLARE_WORK(sched_itmt_work, intel_pstste_sched_itmt_work_fn);
-
- +#define CPPC_MAX_PERF U8_MAX
- +
- static void intel_pstate_set_itmt_prio(int cpu)
- {
- struct cppc_perf_caps cppc_perf;
- @@ -345,6 +347,14 @@ static void intel_pstate_set_itmt_prio(int cpu)
- if (ret)
- return;
-
- + /*
- + * On some systems with overclocking enabled, CPPC.highest_perf is hardcoded to 0xff.
- + * In this case we can't use CPPC.highest_perf to enable ITMT.
- + * In this case we can look at MSR_HWP_CAPABILITIES bits [8:0] to decide.
- + */
- + if (cppc_perf.highest_perf == CPPC_MAX_PERF)
- + cppc_perf.highest_perf = HWP_HIGHEST_PERF(READ_ONCE(all_cpu_data[cpu]->hwp_cap_cached));
- +
- /*
- * The priorities can be set regardless of whether or not
- * sched_set_itmt_support(true) has been called and it is valid to
- --
- 2.34.1
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