[PATCH v4 18/19] cpufreq/amd-pstate: Stop caching EPP

Mario Limonciello
2025-02-19T21:03:34Z

EPP values are cached in the cpudata structure per CPU. This is needless
though because they are also cached in the CPPC request variable.

Drop the separate cache for EPP values and always reference the CPPC
request variable when needed.

Reviewed-by: Dhananjay Ugwekar <dhananjay.ugwekar@amd.com>
Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
---
drivers/cpufreq/amd-pstate.c | 20 ++++++++++----------
drivers/cpufreq/amd-pstate.h | 1 -
2 files changed, 10 insertions(+), 11 deletions(-)

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index f152636cecbeb..408e63aff377a 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -268,8 +268,6 @@ static int msr_update_perf(struct cpufreq_policy *policy, u8 min_perf,
}

WRITE_ONCE(cpudata->cppc_req_cached, value);
- if (epp != cpudata->epp_cached)
- WRITE_ONCE(cpudata->epp_cached, epp);

return 0;
}
@@ -318,7 +316,6 @@ static int msr_set_epp(struct cpufreq_policy *policy, u8 epp)
}

/* update both so that msr_update_perf() can effectively check */
- WRITE_ONCE(cpudata->epp_cached, epp);
WRITE_ONCE(cpudata->cppc_req_cached, value);

return ret;
@@ -335,9 +332,12 @@ static int shmem_set_epp(struct cpufreq_policy *policy, u8 epp)
{
struct amd_cpudata *cpudata = policy->driver_data;
struct cppc_perf_ctrls perf_ctrls;
+ u8 epp_cached;
u64 value;
int ret;

+
+ epp_cached = FIELD_GET(AMD_CPPC_EPP_PERF_MASK, cpudata->cppc_req_cached);
if (trace_amd_pstate_epp_perf_enabled()) {
union perf_cached perf = cpudata->perf;

@@ -348,10 +348,10 @@ static int shmem_set_epp(struct cpufreq_policy *policy, u8 epp)
FIELD_GET(AMD_CPPC_MAX_PERF_MASK,
cpudata->cppc_req_cached),
policy->boost_enabled,
- epp != cpudata->epp_cached);
+ epp != epp_cached);
}

- if (epp == cpudata->epp_cached)
+ if (epp == epp_cached)
return 0;

perf_ctrls.energy_perf = epp;
@@ -360,7 +360,6 @@ static int shmem_set_epp(struct cpufreq_policy *policy, u8 epp)
pr_debug("failed to set energy perf value (%d)\n", ret);
return ret;
}
- WRITE_ONCE(cpudata->epp_cached, epp);

value = READ_ONCE(cpudata->cppc_req_cached);
value &= ~AMD_CPPC_EPP_PERF_MASK;
@@ -1195,9 +1194,11 @@ static ssize_t show_energy_performance_preference(
struct cpufreq_policy *policy, char *buf)
{
struct amd_cpudata *cpudata = policy->driver_data;
- u8 preference;
+ u8 preference, epp;
+
+ epp = FIELD_GET(AMD_CPPC_EPP_PERF_MASK, cpudata->cppc_req_cached);

- switch (cpudata->epp_cached) {
+ switch (epp) {
case AMD_CPPC_EPP_PERFORMANCE:
preference = EPP_INDEX_PERFORMANCE;
break;
@@ -1560,7 +1561,7 @@ static int amd_pstate_epp_update_limit(struct cpufreq_policy *policy)
if (cpudata->policy == CPUFREQ_POLICY_PERFORMANCE)
epp = 0;
else
- epp = READ_ONCE(cpudata->epp_cached);
+ epp = FIELD_GET(AMD_CPPC_EPP_PERF_MASK, cpudata->cppc_req_cached);

perf = READ_ONCE(cpudata->perf);

@@ -1605,7 +1606,6 @@ static int amd_pstate_epp_cpu_online(struct cpufreq_policy *policy)
cpudata->suspended = false;

return 0;
-
}

static int amd_pstate_epp_cpu_offline(struct cpufreq_policy *policy)
diff --git a/drivers/cpufreq/amd-pstate.h b/drivers/cpufreq/amd-pstate.h
index 1a52582dbac9d..13918853f0a82 100644
--- a/drivers/cpufreq/amd-pstate.h
+++ b/drivers/cpufreq/amd-pstate.h
@@ -100,7 +100,6 @@ struct amd_cpudata {
bool hw_prefcore;

/* EPP feature related attributes*/
- u8 epp_cached;
u32 policy;
bool suspended;
u8 epp_default;
--
2.43.0