Re: [PATCH v2 14/17] cpufreq/amd-pstate: Update cppc_req_cached for shared mem EPP writes

[Gautham R. Shenoy]

On Fri, Feb 14, 2025 at 06:52:41PM -0600, Mario Limonciello wrote:
> From: Mario Limonciello <mario.limonciello@xxxxxxx>
> 
> 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@xxxxxxx>



> 
> Reviewed-by: Dhananjay Ugwekar <dhananjay.ugwekar@xxxxxxx>
> Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx>
> ---
>  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.