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Subject[PATCH v3] cpufreq: intel_pstate: Fix policy data management in passive mode
Date
From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

The policy->cpuinfo.max_freq and policy->max updates in
intel_cpufreq_turbo_update() are excessive as they are done for no
good reason and may lead to problems in principle, so they should be
dropped. However, after dropping them intel_cpufreq_turbo_update()
becomes almost entirely pointless, because the check made by it is
made again down the road in intel_pstate_prepare_request(). The
only thing in it that still needs to be done is the call to
update_turbo_state(), so drop intel_cpufreq_turbo_update() altogether
and make its callers invoke update_turbo_state() directly instead of
it.

In addition to that, fix intel_cpufreq_verify_policy() so that it
checks global.no_turbo in addition to global.turbo_disabled when
updating policy->cpuinfo.max_freq to make it consistent with
intel_pstate_verify_policy().

Fixes: 001c76f05b01 (cpufreq: intel_pstate: Generic governors support)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---

v2 -> v3:
Make the previous callers of intel_cpufreq_turbo_update() invoke
update_turbo_state() directly (since it was called by the former).

-> v2:
Drop intel_cpufreq_turbo_update() as it is pointless without the
excessive updates that need to be dropped.

---
drivers/cpufreq/intel_pstate.c | 29 ++++++-----------------------
1 file changed, 6 insertions(+), 23 deletions(-)

Index: linux-pm/drivers/cpufreq/intel_pstate.c
===================================================================
--- linux-pm.orig/drivers/cpufreq/intel_pstate.c
+++ linux-pm/drivers/cpufreq/intel_pstate.c
@@ -2247,7 +2247,7 @@ static int intel_cpufreq_verify_policy(s
struct cpudata *cpu = all_cpu_data[policy->cpu];

update_turbo_state();
- policy->cpuinfo.max_freq = global.turbo_disabled ?
+ policy->cpuinfo.max_freq = global.no_turbo || global.turbo_disabled ?
cpu->pstate.max_freq : cpu->pstate.turbo_freq;

cpufreq_verify_within_cpu_limits(policy);
@@ -2255,26 +2255,6 @@ static int intel_cpufreq_verify_policy(s
return 0;
}

-static unsigned int intel_cpufreq_turbo_update(struct cpudata *cpu,
- struct cpufreq_policy *policy,
- unsigned int target_freq)
-{
- unsigned int max_freq;
-
- update_turbo_state();
-
- max_freq = global.no_turbo || global.turbo_disabled ?
- cpu->pstate.max_freq : cpu->pstate.turbo_freq;
- policy->cpuinfo.max_freq = max_freq;
- if (policy->max > max_freq)
- policy->max = max_freq;
-
- if (target_freq > max_freq)
- target_freq = max_freq;
-
- return target_freq;
-}
-
static int intel_cpufreq_target(struct cpufreq_policy *policy,
unsigned int target_freq,
unsigned int relation)
@@ -2283,8 +2263,10 @@ static int intel_cpufreq_target(struct c
struct cpufreq_freqs freqs;
int target_pstate;

+ update_turbo_state();
+
freqs.old = policy->cur;
- freqs.new = intel_cpufreq_turbo_update(cpu, policy, target_freq);
+ freqs.new = target_freq;

cpufreq_freq_transition_begin(policy, &freqs);
switch (relation) {
@@ -2316,7 +2298,8 @@ static unsigned int intel_cpufreq_fast_s
struct cpudata *cpu = all_cpu_data[policy->cpu];
int target_pstate;

- target_freq = intel_cpufreq_turbo_update(cpu, policy, target_freq);
+ update_turbo_state();
+
target_pstate = DIV_ROUND_UP(target_freq, cpu->pstate.scaling);
target_pstate = intel_pstate_prepare_request(cpu, target_pstate);
intel_pstate_update_pstate(cpu, target_pstate);
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