Re: [PATCH 01/11] cpufreq: amd-pstate: optimiza the initial frequency values verification

Mario Limonciello
2024-05-07T14:44:06Z

The title has a typo s/optimiza/optimize/

On 5/7/2024 02:15, Perry Yuan wrote:
> To enhance the debugging capability of the driver loading failure for
> broken CPPC ACPI tables, we can optimize the expression by moving the

Remove the "we" here.

> verification of `min_freq`, `nominal_freq`, and other dependency values
> to the `amd_pstate_init_freq()` function where they are initialized.
> If any of these values are incorrect, the `amd-pstate` driver will not be registered.
>
> By ensuring that these values are correct before they are used, it will facilitate
> the debugging process when encountering driver loading failures due to faulty CPPC
> ACPI tables from BIOS
>
> Signed-off-by: Perry Yuan <perry.yuan@amd.com>
> ---
> drivers/cpufreq/amd-pstate.c | 35 ++++++++++++++++++-----------------
> 1 file changed, 18 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 2db095867d03..be7f2d3c86b6 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -873,6 +873,24 @@ static int amd_pstate_init_freq(struct amd_cpudata *cpudata)
> WRITE_ONCE(cpudata->nominal_freq, nominal_freq);
> WRITE_ONCE(cpudata->max_freq, max_freq);
>
> + /**
> + * Below values need to be initialized correctly, otherwise driver will be failed to load

"will fail to load"

> + * max_freq is calculated accoreding to (nominal_freq * highest_perf)/nominal_perf

according to

> + * lowest_nonlinear_freq is a value between [min_freq, nominal_freq]
> + * Check _CPC in ACPI table ojbects if any values are incorrect

objects

> + */
> + if (min_freq <= 0 || max_freq <= 0 || nominal_freq <= 0 || min_freq > max_freq) {
> + pr_err("min_freq(%d) or max_freq(%d) or nominal_freq(%d) value is incorrect\n",
> + min_freq, max_freq, nominal_freq);
> + return -EINVAL;
> + }
> +
> + if (lowest_nonlinear_freq <= min_freq || lowest_nonlinear_freq > nominal_freq * 1000) {
> + pr_err("lowest_nonlinear_freq(%d) value is out of range [min_freq(%d), nominal_freq(%d)]\n",
> + lowest_nonlinear_freq, min_freq, nominal_freq * 1000);
> + return -EINVAL;
> + }
> +
> return 0;
> }
>
> @@ -911,15 +929,6 @@ static int amd_pstate_cpu_init(struct cpufreq_policy *policy)
> max_freq = READ_ONCE(cpudata->max_freq);
> nominal_freq = READ_ONCE(cpudata->nominal_freq);
>
> - if (min_freq <= 0 || max_freq <= 0 ||
> - nominal_freq <= 0 || min_freq > max_freq) {
> - dev_err(dev,
> - "min_freq(%d) or max_freq(%d) or nominal_freq (%d) value is incorrect, check _CPC in ACPI tables\n",
> - min_freq, max_freq, nominal_freq);
> - ret = -EINVAL;
> - goto free_cpudata1;
> - }
> -
> policy->cpuinfo.transition_latency = amd_pstate_get_transition_latency(policy->cpu);
> policy->transition_delay_us = amd_pstate_get_transition_delay_us(policy->cpu);
>
> @@ -1372,14 +1381,6 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
> min_freq = READ_ONCE(cpudata->min_freq);
> max_freq = READ_ONCE(cpudata->max_freq);
> nominal_freq = READ_ONCE(cpudata->nominal_freq);
> - if (min_freq <= 0 || max_freq <= 0 ||
> - nominal_freq <= 0 || min_freq > max_freq) {
> - dev_err(dev,
> - "min_freq(%d) or max_freq(%d) or nominal_freq(%d) value is incorrect, check _CPC in ACPI tables\n",
> - min_freq, max_freq, nominal_freq);
> - ret = -EINVAL;
> - goto free_cpudata1;
> - }
>
> policy->cpuinfo.min_freq = min_freq;
> policy->cpuinfo.max_freq = max_freq;