Re: [PATCH v7 6/6] cpufreq:amd-pstate: initialize capabilities in amd_pstate_init_perf

[Gautham R. Shenoy]

Hello Perry,

On Wed, Mar 13, 2024 at 05:59:18PM +0800, Perry Yuan wrote:
> Moved the initialization of some perf and frequency values related
> to cpudata to the amd_pstate_init_perf and cppc_init_perf functions.
> It can avoid duplicate calls to cppc_get_perf_caps function.

Does it make sense to fold this into Patch 2 where you are caching the
nominal frequency for later use ?

Otherwise, this patch looks good to me.

--
Thanks and Regards
gautham.

> 
> Signed-off-by: Perry Yuan <perry.yuan@xxxxxxx>
> ---
>  drivers/cpufreq/amd-pstate.c | 43 ++++++++++++++----------------------
>  include/linux/amd-pstate.h   |  1 +
>  2 files changed, 18 insertions(+), 26 deletions(-)
> 
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 59bcdf829c93..3877d4ecb5d4 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -330,12 +330,18 @@ static int pstate_init_perf(struct amd_cpudata *cpudata)
>  {
>  	u64 cap1;
>  	u32 highest_perf;
> +	struct cppc_perf_caps cppc_perf;
> +	int ret;
>  
> -	int ret = rdmsrl_safe_on_cpu(cpudata->cpu, MSR_AMD_CPPC_CAP1,
> +	ret = rdmsrl_safe_on_cpu(cpudata->cpu, MSR_AMD_CPPC_CAP1,
>  				     &cap1);
>  	if (ret)
>  		return ret;
>  
> +	ret = cppc_get_perf_caps(cpudata->cpu, &cppc_perf);
> +	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
> @@ -353,6 +359,9 @@ static int pstate_init_perf(struct amd_cpudata *cpudata)
>  	WRITE_ONCE(cpudata->lowest_perf, AMD_CPPC_LOWEST_PERF(cap1));
>  	WRITE_ONCE(cpudata->prefcore_ranking, AMD_CPPC_HIGHEST_PERF(cap1));
>  	WRITE_ONCE(cpudata->min_limit_perf, AMD_CPPC_LOWEST_PERF(cap1));
> +	WRITE_ONCE(cpudata->lowest_freq, cppc_perf.lowest_freq);
> +	WRITE_ONCE(cpudata->nominal_freq, cppc_perf.nominal_freq);
> +
>  	return 0;
>  }
>  
> @@ -360,8 +369,9 @@ static int cppc_init_perf(struct amd_cpudata *cpudata)
>  {
>  	struct cppc_perf_caps cppc_perf;
>  	u32 highest_perf;
> +	int ret;
>  
> -	int ret = cppc_get_perf_caps(cpudata->cpu, &cppc_perf);
> +	ret = cppc_get_perf_caps(cpudata->cpu, &cppc_perf);
>  	if (ret)
>  		return ret;
>  
> @@ -378,6 +388,8 @@ static int cppc_init_perf(struct amd_cpudata *cpudata)
>  	WRITE_ONCE(cpudata->lowest_perf, cppc_perf.lowest_perf);
>  	WRITE_ONCE(cpudata->prefcore_ranking, cppc_perf.highest_perf);
>  	WRITE_ONCE(cpudata->min_limit_perf, cppc_perf.lowest_perf);
> +	WRITE_ONCE(cpudata->lowest_freq, cppc_perf.lowest_freq);
> +	WRITE_ONCE(cpudata->nominal_freq, cppc_perf.nominal_freq);
>  
>  	if (cppc_state == AMD_PSTATE_ACTIVE)
>  		return 0;
> @@ -642,17 +654,12 @@ static void amd_pstate_adjust_perf(unsigned int cpu,
>  
>  static int amd_get_min_freq(struct amd_cpudata *cpudata)
>  {
> -	struct cppc_perf_caps cppc_perf;
>  	u32 lowest_freq;
>  
> -	int ret = cppc_get_perf_caps(cpudata->cpu, &cppc_perf);
> -	if (ret)
> -		return ret;
> -
>  	if (quirks && quirks->lowest_freq)
>  		lowest_freq = quirks->lowest_freq;
>  	else
> -		lowest_freq = cppc_perf.lowest_freq;
> +		lowest_freq = READ_ONCE(cpudata->lowest_freq);
>  
>  	/* Switch to khz */
>  	return lowest_freq * 1000;
> @@ -660,14 +667,9 @@ static int amd_get_min_freq(struct amd_cpudata *cpudata)
>  
>  static int amd_get_max_freq(struct amd_cpudata *cpudata)
>  {
> -	struct cppc_perf_caps cppc_perf;
>  	u32 max_perf, max_freq, nominal_freq, nominal_perf;
>  	u64 boost_ratio;
>  
> -	int ret = cppc_get_perf_caps(cpudata->cpu, &cppc_perf);
> -	if (ret)
> -		return ret;
> -
>  	nominal_freq = READ_ONCE(cpudata->nominal_freq);
>  	nominal_perf = READ_ONCE(cpudata->nominal_perf);
>  	max_perf = READ_ONCE(cpudata->highest_perf);
> @@ -683,36 +685,25 @@ static int amd_get_max_freq(struct amd_cpudata *cpudata)
>  
>  static int amd_get_nominal_freq(struct amd_cpudata *cpudata)
>  {
> -	struct cppc_perf_caps cppc_perf;
>  	u32 nominal_freq;
>  
> -	int ret = cppc_get_perf_caps(cpudata->cpu, &cppc_perf);
> -	if (ret)
> -		return ret;
> -
>  	if (quirks && quirks->nominal_freq)
>  		nominal_freq = quirks->nominal_freq;
>  	else
> -		nominal_freq = cppc_perf.nominal_freq;
> +		nominal_freq = READ_ONCE(cpudata->nominal_freq);
>  
>  	return nominal_freq;
>  }
>  
>  static int amd_get_lowest_nonlinear_freq(struct amd_cpudata *cpudata)
>  {
> -	struct cppc_perf_caps cppc_perf;
>  	u32 lowest_nonlinear_freq, lowest_nonlinear_perf,
>  	    nominal_freq, nominal_perf;
>  	u64 lowest_nonlinear_ratio;
>  
> -	int ret = cppc_get_perf_caps(cpudata->cpu, &cppc_perf);
> -	if (ret)
> -		return ret;
> -
>  	nominal_freq = READ_ONCE(cpudata->nominal_freq);
>  	nominal_perf = READ_ONCE(cpudata->nominal_perf);
> -
> -	lowest_nonlinear_perf = cppc_perf.lowest_nonlinear_perf;
> +	lowest_nonlinear_perf = READ_ONCE(cpudata->lowest_nonlinear_perf);
>  
>  	lowest_nonlinear_ratio = div_u64(lowest_nonlinear_perf << SCHED_CAPACITY_SHIFT,
>  					 nominal_perf);
> diff --git a/include/linux/amd-pstate.h b/include/linux/amd-pstate.h
> index 7b2cbb892fd9..1fbbe75c3dcc 100644
> --- a/include/linux/amd-pstate.h
> +++ b/include/linux/amd-pstate.h
> @@ -88,6 +88,7 @@ struct amd_cpudata {
>  	u32	min_freq;
>  	u32	nominal_freq;
>  	u32	lowest_nonlinear_freq;
> +	u32	lowest_freq;
>  
>  	struct amd_aperf_mperf cur;
>  	struct amd_aperf_mperf prev;
> -- 
> 2.34.1
>