linux-kernel - Re: [PATCH v7 4/6] cpufreq: amd-pstate: fix the MSR highest perf will be reset issue while cpb boost off

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Message-ID: <ZieV2ZgVh0LZISuO@amd.com>
Date: Tue, 23 Apr 2024 19:04:57 +0800
From: Huang Rui <ray.huang@....com>
To: "Yuan, Perry" <Perry.Yuan@....com>
Cc: "rafael.j.wysocki@...el.com" <rafael.j.wysocki@...el.com>,
	"Limonciello, Mario" <Mario.Limonciello@....com>,
	"viresh.kumar@...aro.org" <viresh.kumar@...aro.org>,
	"Shenoy, Gautham Ranjal" <gautham.shenoy@....com>,
	"Petkov, Borislav" <Borislav.Petkov@....com>,
	"Deucher, Alexander" <Alexander.Deucher@....com>,
	"Huang, Shimmer" <Shimmer.Huang@....com>,
	"oleksandr@...alenko.name" <oleksandr@...alenko.name>,
	"Du, Xiaojian" <Xiaojian.Du@....com>,
	"Meng, Li (Jassmine)" <Li.Meng@....com>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v7 4/6] cpufreq: amd-pstate: fix the MSR highest perf
 will be reset issue while cpb boost off

On Tue, Apr 23, 2024 at 04:40:57PM +0800, Yuan, Perry wrote:
> From: Perry Yuan <Perry.Yuan@....com>
> 
> Select the min perf to fix the highest perf value while update pstate
> CPPC request MSR register, here we need to limit the max perf value when
> CPU boost is disabled in case of that highest perf value in the MSR will be
> reset to original highest perf value which cause the BOOST control
> failed.
> 
> Signed-off-by: Perry Yuan <Perry.Yuan@....com>

Acked-by: Huang Rui <ray.huang@....com>

> ---
>  drivers/cpufreq/amd-pstate.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 49eeb38fcf20..22e5b84dbe28 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -476,6 +476,7 @@ static void amd_pstate_update(struct amd_cpudata *cpudata, u32 min_perf,
>  			      u32 des_perf, u32 max_perf, bool fast_switch, int gov_flags)
>  {
>  	u64 prev = READ_ONCE(cpudata->cppc_req_cached);
> +	u32 nominal_perf = READ_ONCE(cpudata->nominal_perf);
>  	u64 value = prev;
>  
>  	min_perf = clamp_t(unsigned long, min_perf, cpudata->min_limit_perf,
> @@ -495,6 +496,10 @@ static void amd_pstate_update(struct amd_cpudata *cpudata, u32 min_perf,
>  	value &= ~AMD_CPPC_DES_PERF(~0L);
>  	value |= AMD_CPPC_DES_PERF(des_perf);
>  
> +	/* limit the max perf when core performance boost feature is disabled */
> +	if (!amd_pstate_global_params.cpb_boost)
> +		max_perf = min_t(unsigned long, nominal_perf, max_perf);
> +
>  	value &= ~AMD_CPPC_MAX_PERF(~0L);
>  	value |= AMD_CPPC_MAX_PERF(max_perf);
>  
> -- 
> 2.34.1
>