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Subject[PATCH] cpufreq/cppc: changing highest_perf to nominal_perf in cppc_cpufreq_cpu_init()
Date
When turning on turbo, if frequency configuration takes effect slowly,
the updated policy->cur may be equal to the frequency configured in
governor->limits(), performance governor will not adjust the frequency,
configured frequency will remain at turbo-freq.

Simplified call stack looks as follows:
cpufreq_register_driver(&cppc_cpufreq_driver)
...
cppc_cpufreq_cpu_init()
cppc_get_perf_caps()
policy->max = cppc_perf_to_khz(caps, caps->nominal_perf)
cppc_set_perf(highest_perf) // set highest_perf
policy->cur = cpufreq_driver->get() // if cur == policy->max
cpufreq_init_policy()
...
cpufreq_start_governor() // governor: performance
new_freq = cpufreq_driver->get() // if new_freq == policy->max
if (policy->cur != new_freq)
cpufreq_out_of_sync(policy, new_freq)
...
policy->cur = new_freq
...
policy->governor->limits()
__cpufreq_driver_target(policy->max)
if (policy->cur==target)
// generate error, keep set highest_perf
ret
cppc_set_perf(target)

Fix this by changing highest_perf to nominal_perf in cppc_cpufreq_cpu_init().

Fixes: 5477fb3bd1e8 ("ACPI / CPPC: Add a CPUFreq driver for use with CPPC")
Signed-off-by: liwei <liwei728@huawei.com>
---
drivers/cpufreq/cppc_cpufreq.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c
index 64420d9cfd1e..db04a82b8a97 100644
--- a/drivers/cpufreq/cppc_cpufreq.c
+++ b/drivers/cpufreq/cppc_cpufreq.c
@@ -669,14 +669,14 @@ static int cppc_cpufreq_cpu_init(struct cpufreq_policy *policy)
if (caps->highest_perf > caps->nominal_perf)
boost_supported = true;

- /* Set policy->cur to max now. The governors will adjust later. */
- policy->cur = cppc_perf_to_khz(caps, caps->highest_perf);
- cpu_data->perf_ctrls.desired_perf = caps->highest_perf;
+ /* Set policy->cur to norm now. */
+ policy->cur = cppc_perf_to_khz(caps, caps->nominal_perf);
+ cpu_data->perf_ctrls.desired_perf = caps->nominal_perf;

ret = cppc_set_perf(cpu, &cpu_data->perf_ctrls);
if (ret) {
pr_debug("Err setting perf value:%d on CPU:%d. ret:%d\n",
- caps->highest_perf, cpu, ret);
+ caps->nominal_perf, cpu, ret);
goto out;
}

--
2.25.1

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