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Subject[PATCH] cpufreq: intel_pstate: Simplify intel_pstate_update_perf_limits()
Date
From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Because pstate.max_freq is always equal to the product of
pstate.max_pstate and pstate.scaling and, analogously,
pstate.turbo_freq is always equal to the product of
pstate.turbo_pstate and pstate.scaling, the result of the
max_policy_perf computation in intel_pstate_update_perf_limits() is
always equal to the quotient of policy_max and pstate.scaling,
regardless of whether or not turbo is disabled. Analogously, the
result of min_policy_perf in intel_pstate_update_perf_limits() is
always equal to the quotient of policy_min and pstate.scaling.

Accordingly, intel_pstate_update_perf_limits() need not check
whether or not turbo is enabled at all and in order to compute
max_policy_perf and min_policy_perf it can always divide policy_max
and policy_min, respectively, by pstate.scaling. Make it do so.

While at it, move the definition and initialization of the
turbo_max local variable to the code branch using it.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---

On top of linux-next.

---
drivers/cpufreq/intel_pstate.c | 22 ++++++----------------
1 file changed, 6 insertions(+), 16 deletions(-)

Index: linux-pm/drivers/cpufreq/intel_pstate.c
===================================================================
--- linux-pm.orig/drivers/cpufreq/intel_pstate.c
+++ linux-pm/drivers/cpufreq/intel_pstate.c
@@ -2195,9 +2195,8 @@ static void intel_pstate_update_perf_lim
unsigned int policy_min,
unsigned int policy_max)
{
+ int scaling = cpu->pstate.scaling;
int32_t max_policy_perf, min_policy_perf;
- int max_state, turbo_max;
- int max_freq;

/*
* HWP needs some special consideration, because HWP_REQUEST uses
@@ -2206,33 +2205,24 @@ static void intel_pstate_update_perf_lim
if (hwp_active)
intel_pstate_get_hwp_cap(cpu);

- if (global.no_turbo || global.turbo_disabled) {
- max_state = cpu->pstate.max_pstate;
- max_freq = cpu->pstate.max_freq;
- } else {
- max_state = cpu->pstate.turbo_pstate;
- max_freq = cpu->pstate.turbo_freq;
- }
-
- turbo_max = cpu->pstate.turbo_pstate;
-
- max_policy_perf = max_state * policy_max / max_freq;
+ max_policy_perf = policy_max / scaling;
if (policy_max == policy_min) {
min_policy_perf = max_policy_perf;
} else {
- min_policy_perf = max_state * policy_min / max_freq;
+ min_policy_perf = policy_min / scaling;
min_policy_perf = clamp_t(int32_t, min_policy_perf,
0, max_policy_perf);
}

- pr_debug("cpu:%d max_state %d min_policy_perf:%d max_policy_perf:%d\n",
- cpu->cpu, max_state, min_policy_perf, max_policy_perf);
+ pr_debug("cpu:%d min_policy_perf:%d max_policy_perf:%d\n",
+ cpu->cpu, min_policy_perf, max_policy_perf);

/* Normalize user input to [min_perf, max_perf] */
if (per_cpu_limits) {
cpu->min_perf_ratio = min_policy_perf;
cpu->max_perf_ratio = max_policy_perf;
} else {
+ int turbo_max = cpu->pstate.turbo_pstate;
int32_t global_min, global_max;

/* Global limits are in percent of the maximum turbo P-state. */


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