linux-kernel - Re: [PATCH v2 2/2] cpufreq/amd-pstate: Fix the scaling_max_freq setting on shared memory CPPC systems

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Date: Tue, 2 Jul 2024 12:49:26 -0500
From: Mario Limonciello <mario.limonciello@....com>
To: Dhananjay Ugwekar <Dhananjay.Ugwekar@....com>, rafael@...nel.org,
 viresh.kumar@...aro.org, gautham.shenoy@....com, perry.yuan@....com,
 skhan@...uxfoundation.org, li.meng@....com, ray.huang@....com
Cc: linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
 David Arcari <darcari@...hat.com>
Subject: Re: [PATCH v2 2/2] cpufreq/amd-pstate: Fix the scaling_max_freq
 setting on shared memory CPPC systems

On 7/2/2024 3:14, Dhananjay Ugwekar wrote:
> On shared memory CPPC systems, with amd_pstate=active mode, the change
> in scaling_max_freq doesn't get written to the shared memory
> region. Due to this, the writes to the scaling_max_freq sysfs file
> don't take effect. Fix this by propagating the scaling_max_freq
> changes to the shared memory region.
> 
> Fixes: ffa5096a7c33 ("cpufreq: amd-pstate: implement Pstate EPP support for the AMD processors")
> Reported-by: David Arcari <darcari@...hat.com>
> Signed-off-by: Dhananjay Ugwekar <Dhananjay.Ugwekar@....com>
Reviewed-by: Mario Limonciello <mario.limonciello@....com>
> ---
>   drivers/cpufreq/amd-pstate.c | 43 +++++++++++++++++++-----------------
>   1 file changed, 23 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 9ad62dbe8bfb..a092b13ffbc2 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -247,6 +247,26 @@ static int amd_pstate_get_energy_pref_index(struct amd_cpudata *cpudata)
>   	return index;
>   }
>   
> +static void pstate_update_perf(struct amd_cpudata *cpudata, u32 min_perf,
> +			       u32 des_perf, u32 max_perf, bool fast_switch)
> +{
> +	if (fast_switch)
> +		wrmsrl(MSR_AMD_CPPC_REQ, READ_ONCE(cpudata->cppc_req_cached));
> +	else
> +		wrmsrl_on_cpu(cpudata->cpu, MSR_AMD_CPPC_REQ,
> +			      READ_ONCE(cpudata->cppc_req_cached));
> +}
> +
> +DEFINE_STATIC_CALL(amd_pstate_update_perf, pstate_update_perf);
> +
> +static inline void amd_pstate_update_perf(struct amd_cpudata *cpudata,
> +					  u32 min_perf, u32 des_perf,
> +					  u32 max_perf, bool fast_switch)
> +{
> +	static_call(amd_pstate_update_perf)(cpudata, min_perf, des_perf,
> +					    max_perf, fast_switch);
> +}
> +
>   static int amd_pstate_set_epp(struct amd_cpudata *cpudata, u32 epp)
>   {
>   	int ret;
> @@ -263,6 +283,9 @@ static int amd_pstate_set_epp(struct amd_cpudata *cpudata, u32 epp)
>   		if (!ret)
>   			cpudata->epp_cached = epp;
>   	} else {
> +		amd_pstate_update_perf(cpudata, cpudata->min_limit_perf, 0U,
> +					     cpudata->max_limit_perf, false);
> +
>   		perf_ctrls.energy_perf = epp;
>   		ret = cppc_set_epp_perf(cpudata->cpu, &perf_ctrls, 1);
>   		if (ret) {
> @@ -452,16 +475,6 @@ static inline int amd_pstate_init_perf(struct amd_cpudata *cpudata)
>   	return static_call(amd_pstate_init_perf)(cpudata);
>   }
>   
> -static void pstate_update_perf(struct amd_cpudata *cpudata, u32 min_perf,
> -			       u32 des_perf, u32 max_perf, bool fast_switch)
> -{
> -	if (fast_switch)
> -		wrmsrl(MSR_AMD_CPPC_REQ, READ_ONCE(cpudata->cppc_req_cached));
> -	else
> -		wrmsrl_on_cpu(cpudata->cpu, MSR_AMD_CPPC_REQ,
> -			      READ_ONCE(cpudata->cppc_req_cached));
> -}
> -
>   static void cppc_update_perf(struct amd_cpudata *cpudata,
>   			     u32 min_perf, u32 des_perf,
>   			     u32 max_perf, bool fast_switch)
> @@ -475,16 +488,6 @@ static void cppc_update_perf(struct amd_cpudata *cpudata,
>   	cppc_set_perf(cpudata->cpu, &perf_ctrls);
>   }
>   
> -DEFINE_STATIC_CALL(amd_pstate_update_perf, pstate_update_perf);
> -
> -static inline void amd_pstate_update_perf(struct amd_cpudata *cpudata,
> -					  u32 min_perf, u32 des_perf,
> -					  u32 max_perf, bool fast_switch)
> -{
> -	static_call(amd_pstate_update_perf)(cpudata, min_perf, des_perf,
> -					    max_perf, fast_switch);
> -}
> -
>   static inline bool amd_pstate_sample(struct amd_cpudata *cpudata)
>   {
>   	u64 aperf, mperf, tsc;