RE: [PATCH 2/2] cpufreq/amd-pstate: Catch failures for amd_pstate_epp_update_limit()

[Yuan, Perry]

[AMD Official Use Only - AMD Internal Distribution Only]

> -----Original Message-----
> From: Mario Limonciello <superm1@xxxxxxxxxx>
> Sent: Sunday, September 1, 2024 1:01 PM
> To: Shenoy, Gautham Ranjal <gautham.shenoy@xxxxxxx>; Yuan, Perry
> <Perry.Yuan@xxxxxxx>
> Cc: open list:X86 ARCHITECTURE (32-BIT AND 64-BIT) <linux-
> kernel@xxxxxxxxxxxxxxx>; open list:CPU FREQUENCY SCALING FRAMEWORK
> <linux-pm@xxxxxxxxxxxxxxx>; Limonciello, Mario
> <Mario.Limonciello@xxxxxxx>
> Subject: [PATCH 2/2] cpufreq/amd-pstate: Catch failures for
> amd_pstate_epp_update_limit()
>
> From: Mario Limonciello <mario.limonciello@xxxxxxx>
>
> amd_pstate_set_epp() calls cppc_set_epp_perf() which can fail for a variety of
> reasons but this is ignored.  Change the return flow to allow failures.
>
> Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx>

LGTM,

Reviewed-by: Perry Yuan <perry.yuan@xxxxxxx>

> ---
>  drivers/cpufreq/amd-pstate.c | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 89438a3654002..b07be4d945e4d 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -1556,7 +1556,7 @@ static void amd_pstate_epp_cpu_exit(struct
> cpufreq_policy *policy)
>       pr_debug("CPU %d exiting\n", policy->cpu);  }
>
> -static void amd_pstate_epp_update_limit(struct cpufreq_policy *policy)
> +static int amd_pstate_epp_update_limit(struct cpufreq_policy *policy)
>  {
>       struct amd_cpudata *cpudata = policy->driver_data;
>       u32 max_perf, min_perf, min_limit_perf, max_limit_perf; @@ -1606,7
> +1606,7 @@ static void amd_pstate_epp_update_limit(struct cpufreq_policy
> *policy)
>                * This return value can only be negative for shared_memory
>                * systems where EPP register read/write not supported.
>                */
> -             return;
> +             return epp;
>       }
>
>       if (cpudata->policy == CPUFREQ_POLICY_PERFORMANCE) @@ -
> 1619,12 +1619,13 @@ static void amd_pstate_epp_update_limit(struct
> cpufreq_policy *policy)
>       }
>
>       WRITE_ONCE(cpudata->cppc_req_cached, value);
> -     amd_pstate_set_epp(cpudata, epp);
> +     return amd_pstate_set_epp(cpudata, epp);
>  }
>
>  static int amd_pstate_epp_set_policy(struct cpufreq_policy *policy)  {
>       struct amd_cpudata *cpudata = policy->driver_data;
> +     int ret;
>
>       if (!policy->cpuinfo.max_freq)
>               return -ENODEV;
> @@ -1634,7 +1635,9 @@ static int amd_pstate_epp_set_policy(struct
> cpufreq_policy *policy)
>
>       cpudata->policy = policy->policy;
>
> -     amd_pstate_epp_update_limit(policy);
> +     ret = amd_pstate_epp_update_limit(policy);
> +     if (ret)
> +             return ret;
>
>       /*
>        * policy->cur is never updated with the amd_pstate_epp driver, but it
> --
> 2.43.0