linux-kernel - Re: [PATCH v2 14/17] cpufreq/amd-pstate: Update cppc_req

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Message-ID: <Z7NH/xTQgyLE1sY1@BLRRASHENOY1.amd.com>
Date: Mon, 17 Feb 2025 20:00:23 +0530
From: "Gautham R. Shenoy" <gautham.shenoy@....com>
To: Mario Limonciello <superm1@...nel.org>
Cc: Perry Yuan <perry.yuan@....com>,
	Dhananjay Ugwekar <Dhananjay.Ugwekar@....com>,
	"open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <linux-kernel@...r.kernel.org>,
	"open list:CPU FREQUENCY SCALING FRAMEWORK" <linux-pm@...r.kernel.org>,
	Mario Limonciello <mario.limonciello@....com>
Subject: Re: [PATCH v2 14/17] cpufreq/amd-pstate: Update cppc_req_cached for
 shared mem EPP writes

On Fri, Feb 14, 2025 at 06:52:41PM -0600, Mario Limonciello wrote:
> From: Mario Limonciello <mario.limonciello@....com>
> 
> On EPP only writes update the cached variable so that the min/max
> performance controls don't need to be updated again.

This also paves the way to get rid of the cpudata->epp_cached variable
which you do in Patch 17.

LGTM

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



> 
> Reviewed-by: Dhananjay Ugwekar <dhananjay.ugwekar@....com>
> Signed-off-by: Mario Limonciello <mario.limonciello@....com>
> ---
>  drivers/cpufreq/amd-pstate.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 1304bdc23e809..fd2b559f47c5c 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -336,6 +336,7 @@ static int shmem_set_epp(struct cpufreq_policy *policy, u8 epp)
>  {
>  	struct amd_cpudata *cpudata = policy->driver_data;
>  	struct cppc_perf_ctrls perf_ctrls;
> +	u64 value;
>  	int ret;
>  
>  	if (trace_amd_pstate_epp_perf_enabled()) {
> @@ -362,6 +363,11 @@ static int shmem_set_epp(struct cpufreq_policy *policy, u8 epp)
>  	}
>  	WRITE_ONCE(cpudata->epp_cached, epp);
>  
> +	value = READ_ONCE(cpudata->cppc_req_cached);
> +	value &= ~AMD_CPPC_EPP_PERF_MASK;
> +	value |= FIELD_PREP(AMD_CPPC_EPP_PERF_MASK, epp);
> +	WRITE_ONCE(cpudata->cppc_req_cached, value);
> +
>  	return ret;
>  }
>  
> -- 
> 2.43.0
> 

-- 
Thanks and Regards
gautham.