linux-kernel - Re: [PATCH 10/14] cpufreq/amd-pstate: Update cppc_req

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Message-ID: <9c5a60b6-d9ab-470f-9f3a-03f5c872d3de@amd.com>
Date: Tue, 11 Feb 2025 18:31:55 +0530
From: Dhananjay Ugwekar <Dhananjay.Ugwekar@....com>
To: Mario Limonciello <superm1@...nel.org>,
 "Gautham R . Shenoy" <gautham.shenoy@....com>,
 Perry Yuan <perry.yuan@....com>
Cc: "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 10/14] cpufreq/amd-pstate: Update cppc_req_cached for
 shared mem EPP writes

On 2/7/2025 3:26 AM, 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.

Looks good to me,

Reviewed-by: Dhananjay Ugwekar <dhananjay.ugwekar@....com>

Thanks,
Dhananjay

> 
> 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 e66ccfce5893f..754f2d606b371 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -338,6 +338,7 @@ 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;
>  
>  	lockdep_assert_held(&cpudata->lock);
> @@ -366,6 +367,11 @@ 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;
>  }
>