Re: [PATCH v2 2/9] amd-pstate: Update cppc_req_cached in fast_switch case

["Mario Limonciello (AMD) (kernel.org)" <superm1@kernel.org>]

On 3/11/2026 9:01 AM, Gautham R. Shenoy wrote:
> The function msr_update_perf() does not cache the new value that is
> written to MSR_AMD_CPPC_REQ into the variable cpudata->cppc_req_cached
> when the update is happening from the fast path.
> 
> Fix that by caching the value everytime the MSR_AMD_CPPC_REQ gets
> updated.
> 
> This issue was discovered by Claude Opus 4.6 with the aid of Chris
> Mason's AI review-prompts
> (https://github.com/masoncl/review-prompts/tree/main/kernel).
> 
> Assisted-by: Claude:claude-opus-4.6 review-prompts/linux
> Fixes: fff395796917 ("cpufreq/amd-pstate: Always write EPP value when updating perf")
> Signed-off-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
> ---
>   drivers/cpufreq/amd-pstate.c | 1 -
>   1 file changed, 1 deletion(-)
> 
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index d57969c72c9dc..24cdeffbcd40e 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -261,7 +261,6 @@ static int msr_update_perf(struct cpufreq_policy *policy, u8 min_perf,
>   
>   	if (fast_switch) {
>   		wrmsrq(MSR_AMD_CPPC_REQ, value);
> -		return 0;
>   	} else {
>   		int ret = wrmsrq_on_cpu(cpudata->cpu, MSR_AMD_CPPC_REQ, value);
>