[PATCH v14 3/5] cpufreq: amd-pstate: Cap the CPPC.max_perf to nominal_perf if CPB is off

[Mario Limonciello <mario.limonciello@amd.com>]

From: Perry Yuan <Perry.Yuan@amd.com>

When Core Performance Boost is disabled by the user, the
CPPC_REQ.max_perf should not exceed the nominal_perf since by definition
the frequencies between nominal_perf and the highest_perf are in the
boost range. Fix this in amd_pstate_update()

Acked-by: Huang Rui <ray.huang@amd.com>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Signed-off-by: Perry Yuan <Perry.Yuan@amd.com>
Link: https://lore.kernel.org/r/66f55232be01092c423f0523f68b82b80c293943.1718988436.git.perry.yuan@amd.com
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
---
 drivers/cpufreq/amd-pstate.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index 10cce7023208..6992f6169919 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -514,6 +514,7 @@ static void amd_pstate_update(struct amd_cpudata *cpudata, u32 min_perf,
 	unsigned long max_freq;
 	struct cpufreq_policy *policy = cpufreq_cpu_get(cpudata->cpu);
 	u64 prev = READ_ONCE(cpudata->cppc_req_cached);
+	u32 nominal_perf = READ_ONCE(cpudata->nominal_perf);
 	u64 value = prev;
 
 	min_perf = clamp_t(unsigned long, min_perf, cpudata->min_limit_perf,
@@ -536,6 +537,10 @@ static void amd_pstate_update(struct amd_cpudata *cpudata, u32 min_perf,
 	value &= ~AMD_CPPC_DES_PERF(~0L);
 	value |= AMD_CPPC_DES_PERF(des_perf);
 
+	/* limit the max perf when core performance boost feature is disabled */
+	if (!cpudata->boost_supported)
+		max_perf = min_t(unsigned long, nominal_perf, max_perf);
+
 	value &= ~AMD_CPPC_MAX_PERF(~0L);
 	value |= AMD_CPPC_MAX_PERF(max_perf);
 
-- 
2.43.0