Re: [PATCH v3 01/18] cpufreq/amd-pstate: Invalidate cppc_req_cached during suspend
From: Dhananjay Ugwekar
Date: Wed Feb 19 2025 - 01:13:09 EST
On 2/18/2025 3:36 AM, Mario Limonciello wrote:
> From: Mario Limonciello <mario.limonciello@xxxxxxx>
>
> During resume it's possible the firmware didn't restore the CPPC request MSR
> but the kernel thinks the values line up. This leads to incorrect performance
> after resume from suspend.
>
> To fix the issue invalidate the cached value at suspend. During resume use
> the saved values programmed as cached limits.
>
> Reported-by: Miroslav Pavleski <miroslav@xxxxxxxxxxxx>
> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217931
> Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx>
> ---
> drivers/cpufreq/amd-pstate.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index f425fb7ec77d7..12fb63169a24c 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -1611,7 +1611,7 @@ static int amd_pstate_epp_reenable(struct cpufreq_policy *policy)
> max_perf, policy->boost_enabled);
> }
>
> - return amd_pstate_update_perf(cpudata, 0, 0, max_perf, cpudata->epp_cached, false);
> + return amd_pstate_epp_update_limit(policy);
Can we also add the check "if (policy->min != cpudata->min_limit_freq || policy->max != cpudata->max_limit_freq)"
in "amd_pstate_epp_update_limit()" before calling "amd_pstate_update_min_max_limit()". I think it would help in
avoiding some unnecessary calls to the update_min_max_limit() function.
Patch looks good to me otherwise.
Thanks,
Dhananjay
> }
>
> static int amd_pstate_epp_cpu_online(struct cpufreq_policy *policy)
> @@ -1660,6 +1660,9 @@ static int amd_pstate_epp_suspend(struct cpufreq_policy *policy)
> if (cppc_state != AMD_PSTATE_ACTIVE)
> return 0;
>
> + /* invalidate to ensure it's rewritten during resume */
> + cpudata->cppc_req_cached = 0;
> +
> /* set this flag to avoid setting core offline*/
> cpudata->suspended = true;
>