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SubjectRe: [PATCH] cpufreq/cppc: changing highest_perf to nominal_perf in cppc_cpufreq_cpu_init()
CC'ing few folks who are working with the driver.

On 28-04-24, 17:28, liwei wrote:
> 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

--
viresh

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