Re: [PATCH v2 08/11] cpufreq: amd-pstate: Merge amd_pstate_highest_perf_set() into amd_get_boost_ratio_numerator()

["Gautham R. Shenoy" <gautham.shenoy@amd.com>]

On Tue, Sep 03, 2024 at 03:36:58PM -0500, Mario Limonciello wrote:
> From: Mario Limonciello <mario.limonciello@amd.com>
> 
> The special case in amd_pstate_highest_perf_set() is the value used
> for calculating the boost numerator.  Merge this into
> amd_get_boost_ratio_numerator() and then use that to calculate boost
> ratio.
> 
> This allows dropping more special casing of the highest perf value.
> 
> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>

> ---
> v1->v2:
>  * Document that preferred cores will have different values for highest
>    perf.
>  * Fix an uninitialized variable caused by merge
> ---
>  Documentation/admin-guide/pm/amd-pstate.rst |  3 +-
>  arch/x86/kernel/acpi/cppc.c                 | 16 +++++++
>  drivers/cpufreq/amd-pstate.c                | 52 ++++-----------------
>  3 files changed, 28 insertions(+), 43 deletions(-)
> 
> diff --git a/Documentation/admin-guide/pm/amd-pstate.rst b/Documentation/admin-guide/pm/amd-pstate.rst
> index d0324d44f5482..e13915c540648 100644
> --- a/Documentation/admin-guide/pm/amd-pstate.rst
> +++ b/Documentation/admin-guide/pm/amd-pstate.rst
> @@ -251,7 +251,8 @@ performance supported in `AMD CPPC Performance Capability <perf_cap_>`_).
>  In some ASICs, the highest CPPC performance is not the one in the ``_CPC``
>  table, so we need to expose it to sysfs. If boost is not active, but
>  still supported, this maximum frequency will be larger than the one in
> -``cpuinfo``.
> +``cpuinfo``. On systems that support preferred core, the driver will have
> +different values for some cores than others.

Thanks for documenting this.

The patch looks good to me.

Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>


--
Thanks and Regards
gautham.

>  This attribute is read-only.
>  
>  ``amd_pstate_lowest_nonlinear_freq``
> diff --git a/arch/x86/kernel/acpi/cppc.c b/arch/x86/kernel/acpi/cppc.c
> index df367bc359308..956984054bf30 100644
> --- a/arch/x86/kernel/acpi/cppc.c
> +++ b/arch/x86/kernel/acpi/cppc.c
> @@ -9,6 +9,7 @@
>  #include <asm/processor.h>
>  #include <asm/topology.h>
>  
> +#define CPPC_HIGHEST_PERF_PERFORMANCE	196
>  #define CPPC_HIGHEST_PERF_PREFCORE	166
>  
>  enum amd_pref_core {
> @@ -245,6 +246,21 @@ int amd_get_boost_ratio_numerator(unsigned int cpu, u64 *numerator)
>  		*numerator = boost_numerator;
>  		return 0;
>  	}
> +
> +	/*
> +	 * For AMD CPUs with Family ID 19H and Model ID range 0x70 to 0x7f,
> +	 * the highest performance level is set to 196.
> +	 * https://bugzilla.kernel.org/show_bug.cgi?id=218759
> +	 */
> +	if (cpu_feature_enabled(X86_FEATURE_ZEN4)) {
> +		switch (boot_cpu_data.x86_model) {
> +		case 0x70 ... 0x7f:
> +			*numerator = CPPC_HIGHEST_PERF_PERFORMANCE;
> +			return 0;
> +		default:
> +			break;
> +		}
> +	}
>  	*numerator = CPPC_HIGHEST_PERF_PREFCORE;
>  
>  	return 0;
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index c29cdf2d3882c..3ae41af6f041e 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -52,8 +52,6 @@
>  #define AMD_PSTATE_TRANSITION_LATENCY	20000
>  #define AMD_PSTATE_TRANSITION_DELAY	1000
>  #define AMD_PSTATE_FAST_CPPC_TRANSITION_DELAY 600
> -#define CPPC_HIGHEST_PERF_PERFORMANCE	196
> -#define CPPC_HIGHEST_PERF_DEFAULT	166
>  
>  #define AMD_CPPC_EPP_PERFORMANCE		0x00
>  #define AMD_CPPC_EPP_BALANCE_PERFORMANCE	0x80
> @@ -372,43 +370,17 @@ static inline int amd_pstate_enable(bool enable)
>  	return static_call(amd_pstate_enable)(enable);
>  }
>  
> -static u32 amd_pstate_highest_perf_set(struct amd_cpudata *cpudata)
> -{
> -	struct cpuinfo_x86 *c = &cpu_data(0);
> -
> -	/*
> -	 * For AMD CPUs with Family ID 19H and Model ID range 0x70 to 0x7f,
> -	 * the highest performance level is set to 196.
> -	 * https://bugzilla.kernel.org/show_bug.cgi?id=218759
> -	 */
> -	if (c->x86 == 0x19 && (c->x86_model >= 0x70 && c->x86_model <= 0x7f))
> -		return CPPC_HIGHEST_PERF_PERFORMANCE;
> -
> -	return CPPC_HIGHEST_PERF_DEFAULT;
> -}
> -
>  static int pstate_init_perf(struct amd_cpudata *cpudata)
>  {
>  	u64 cap1;
> -	u32 highest_perf;
>  
>  	int ret = rdmsrl_safe_on_cpu(cpudata->cpu, MSR_AMD_CPPC_CAP1,
>  				     &cap1);
>  	if (ret)
>  		return ret;
>  
> -	/* For platforms that do not support the preferred core feature, the
> -	 * highest_pef may be configured with 166 or 255, to avoid max frequency
> -	 * calculated wrongly. we take the AMD_CPPC_HIGHEST_PERF(cap1) value as
> -	 * the default max perf.
> -	 */
> -	if (cpudata->hw_prefcore)
> -		highest_perf = amd_pstate_highest_perf_set(cpudata);
> -	else
> -		highest_perf = AMD_CPPC_HIGHEST_PERF(cap1);
> -
> -	WRITE_ONCE(cpudata->highest_perf, highest_perf);
> -	WRITE_ONCE(cpudata->max_limit_perf, highest_perf);
> +	WRITE_ONCE(cpudata->highest_perf, AMD_CPPC_HIGHEST_PERF(cap1));
> +	WRITE_ONCE(cpudata->max_limit_perf, AMD_CPPC_HIGHEST_PERF(cap1));
>  	WRITE_ONCE(cpudata->nominal_perf, AMD_CPPC_NOMINAL_PERF(cap1));
>  	WRITE_ONCE(cpudata->lowest_nonlinear_perf, AMD_CPPC_LOWNONLIN_PERF(cap1));
>  	WRITE_ONCE(cpudata->lowest_perf, AMD_CPPC_LOWEST_PERF(cap1));
> @@ -420,19 +392,13 @@ static int pstate_init_perf(struct amd_cpudata *cpudata)
>  static int cppc_init_perf(struct amd_cpudata *cpudata)
>  {
>  	struct cppc_perf_caps cppc_perf;
> -	u32 highest_perf;
>  
>  	int ret = cppc_get_perf_caps(cpudata->cpu, &cppc_perf);
>  	if (ret)
>  		return ret;
>  
> -	if (cpudata->hw_prefcore)
> -		highest_perf = amd_pstate_highest_perf_set(cpudata);
> -	else
> -		highest_perf = cppc_perf.highest_perf;
> -
> -	WRITE_ONCE(cpudata->highest_perf, highest_perf);
> -	WRITE_ONCE(cpudata->max_limit_perf, highest_perf);
> +	WRITE_ONCE(cpudata->highest_perf, cppc_perf.highest_perf);
> +	WRITE_ONCE(cpudata->max_limit_perf, cppc_perf.highest_perf);
>  	WRITE_ONCE(cpudata->nominal_perf, cppc_perf.nominal_perf);
>  	WRITE_ONCE(cpudata->lowest_nonlinear_perf,
>  		   cppc_perf.lowest_nonlinear_perf);
> @@ -905,8 +871,8 @@ static u32 amd_pstate_get_transition_latency(unsigned int cpu)
>  static int amd_pstate_init_freq(struct amd_cpudata *cpudata)
>  {
>  	int ret;
> -	u32 min_freq;
> -	u32 highest_perf, max_freq;
> +	u32 min_freq, max_freq;
> +	u64 numerator;
>  	u32 nominal_perf, nominal_freq;
>  	u32 lowest_nonlinear_perf, lowest_nonlinear_freq;
>  	u32 boost_ratio, lowest_nonlinear_ratio;
> @@ -928,8 +894,10 @@ static int amd_pstate_init_freq(struct amd_cpudata *cpudata)
>  
>  	nominal_perf = READ_ONCE(cpudata->nominal_perf);
>  
> -	highest_perf = READ_ONCE(cpudata->highest_perf);
> -	boost_ratio = div_u64(highest_perf << SCHED_CAPACITY_SHIFT, nominal_perf);
> +	ret = amd_get_boost_ratio_numerator(cpudata->cpu, &numerator);
> +	if (ret)
> +		return ret;
> +	boost_ratio = div_u64(numerator << SCHED_CAPACITY_SHIFT, nominal_perf);
>  	max_freq = (nominal_freq * boost_ratio >> SCHED_CAPACITY_SHIFT) * 1000;
>  
>  	lowest_nonlinear_perf = READ_ONCE(cpudata->lowest_nonlinear_perf);
> -- 
> 2.43.0
>