Re: [PATCH 2/8] x86/amd: Rename amd_get_highest_perf() to amd_get_boost_ratio_numerator()

Mario Limonciello
2024-08-27T18:18:51Z

On 8/27/2024 09:42, Gautham R. Shenoy wrote:
> Hello Mario,
>
> On Mon, Aug 26, 2024 at 04:13:52PM -0500, Mario Limonciello wrote:
>> From: Mario Limonciello <mario.limonciello@amd.com>
>>
>> The function name is ambiguous because it returns an intermediate value
>> for calculating maximum frequency rather than the CPPC 'Highest Perf'
>> register.
>>
>> Rename the function to clarify its use and allow the function to return
>> errors. Adjust the consumer in acpi-cpufreq to catch errors.
>>
>> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
> [..snip..]
>
>> --- a/arch/x86/kernel/acpi/cppc.c
>> +++ b/arch/x86/kernel/acpi/cppc.c
>> @@ -79,11 +79,13 @@ static void amd_set_max_freq_ratio(void)
>> return;
>> }
>>
>> - highest_perf = amd_get_highest_perf();
>> + rc = amd_get_boost_ratio_numerator(0, &highest_perf);
>
> The variable is still named highest_perf, here! I suppose that will
> change in a subsequent patch?
>
>
>
>> + if (rc)
>> + pr_debug("Could not retrieve highest performance\n");
>
> I understand that amd_get_boost_ratio_numerator() always returns a 0
> in this patch and thus rc == 0, which means we never enter this "if"
> condition.
>
> However, when rc is non-zero, shouldn't this function return after
> printing the debug message?

Both good points. Will fix for v2.

>
> --
> Thanks and Regards
> gautham.
>
>
>
>
>> nominal_perf = perf_caps.nominal_perf;
>>
>> - if (!highest_perf || !nominal_perf) {
>> - pr_debug("Could not retrieve highest or nominal performance\n");
>> + if (!nominal_perf) {
>> + pr_debug("Could not retrieve nominal performance\n");
>> return;
>> }
>>
>> @@ -117,18 +119,34 @@ void init_freq_invariance_cppc(void)
>> mutex_unlock(&freq_invariance_lock);
>> }
>>
>> -u32 amd_get_highest_perf(void)
>> +/**
>> + * amd_get_boost_ratio_numerator: Get the numerator to use for boost ratio calculation
>> + * @cpu: CPU to get numerator for.
>> + * @numerator: Output variable for numerator.
>> + *
>> + * Determine the numerator to use for calculating the boost ratio on
>> + * a CPU. On systems that support preferred cores, this will be a hardcoded
>> + * value. On other systems this will the highest performance register value.
>> + *
>> + * Return: 0 for success, negative error code otherwise.
>> + */
>> +int amd_get_boost_ratio_numerator(unsigned int cpu, u64 *numerator)
>> {
>> struct cpuinfo_x86 *c = &boot_cpu_data;
>>
>> if (c->x86 == 0x17 && ((c->x86_model >= 0x30 && c->x86_model < 0x40) ||
>> - (c->x86_model >= 0x70 && c->x86_model < 0x80)))
>> - return 166;
>> + (c->x86_model >= 0x70 && c->x86_model < 0x80))) {
>> + *numerator = 166;
>> + return 0;
>> + }
>>
>> if (c->x86 == 0x19 && ((c->x86_model >= 0x20 && c->x86_model < 0x30) ||
>> - (c->x86_model >= 0x40 && c->x86_model < 0x70)))
>> - return 166;
>> + (c->x86_model >= 0x40 && c->x86_model < 0x70))) {
>> + *numerator = 166;
>> + return 0;
>> + }
>> + *numerator = 255;
>>
>> - return 255;
>> + return 0;
>> }
>> -EXPORT_SYMBOL_GPL(amd_get_highest_perf);
>> +EXPORT_SYMBOL_GPL(amd_get_boost_ratio_numerator);
>> diff --git a/drivers/cpufreq/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c
>> index a8ca625a98b89..0f04feb6cafaf 100644
>> --- a/drivers/cpufreq/acpi-cpufreq.c
>> +++ b/drivers/cpufreq/acpi-cpufreq.c
>> @@ -642,10 +642,16 @@ static u64 get_max_boost_ratio(unsigned int cpu)
>> return 0;
>> }
>>
>> - if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD)
>> - highest_perf = amd_get_highest_perf();
>> - else
>> + if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) {
>> + ret = amd_get_boost_ratio_numerator(cpu, &highest_perf);
>> + if (ret) {
>> + pr_debug("CPU%d: Unable to get boost ratio numerator (%d)\n",
>> + cpu, ret);
>> + return 0;
>> + }
>> + } else {
>> highest_perf = perf_caps.highest_perf;
>> + }
>>
>> nominal_perf = perf_caps.nominal_perf;
>>
>> diff --git a/include/acpi/cppc_acpi.h b/include/acpi/cppc_acpi.h
>> index 930b6afba6f4d..f25a881cd46dd 100644
>> --- a/include/acpi/cppc_acpi.h
>> +++ b/include/acpi/cppc_acpi.h
>> @@ -136,6 +136,12 @@ struct cppc_cpudata {
>> cpumask_var_t shared_cpu_map;
>> };
>>
>> +#ifdef CONFIG_CPU_SUP_AMD
>> +extern int amd_get_boost_ratio_numerator(unsigned int cpu, u64 *numerator);
>> +#else /* !CONFIG_CPU_SUP_AMD */
>> +static inline int amd_get_boost_ratio_numerator(unsigned int cpu, u64 *numerator) { return -ENODEV; }
>> +#endif /* !CONFIG_CPU_SUP_AMD */
>> +
>> #ifdef CONFIG_ACPI_CPPC_LIB
>> extern int cppc_get_desired_perf(int cpunum, u64 *desired_perf);
>> extern int cppc_get_nominal_perf(int cpunum, u64 *nominal_perf);
>> --
>> 2.43.0
>>