cpufreq/amd-pstate-ut: Fix amd_pstate_ut_check_freq failure with 'Requested CPU Min frequency' BIOS option

Since commit 608a76b65288 ("cpufreq/amd-pstate: Add support for the
"Requested CPU Min frequency" BIOS option"), amd-pstate driver sets
policy->min to frequency corresponding to bios_min_perf if a valid BIOS
programmed min frequency value is detected.

amd_pstate_ut_check_freq expects policy->min to always match
lowest_nonlinear_freq which does not hold true on platforms with user
configured BIOS min freq.

Update the test case to compare policy->min to bios_min_freq on
platforms that set it. Final comparison is adjusted to account for
insane values by clamping the result within the supported frequency
range.

While at it, move freq_to_perf() and perf_to_freq() helpers to internal
header to allow their use from amd-pstate-ut.

Reviewed-by: Mario Limonciello <superm1@kernel.org>
Fixes: 608a76b65288 ("cpufreq/amd-pstate: Add support for the "Requested CPU Min frequency" BIOS option")
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Link: https://lore.kernel.org/r/20260909102650.4582-1-kprateek.nayak@amd.com
Signed-off-by: Mario Limonciello <superm1@kernel.org>

3 files changed, 36 insertions, 14 deletions

diff --git a/drivers/cpufreq/amd-pstate-ut.c b/drivers/cpufreq/amd-pstate-ut.c
index e23773680e05..c2c1a166b3a9 100644
--- a/drivers/cpufreq/amd-pstate-ut.c
+++ b/drivers/cpufreq/amd-pstate-ut.c
@@ -226,11 +226,14 @@ static int amd_pstate_ut_check_freq(u32 index)
 	for_each_online_cpu(cpu) {
 		struct cpufreq_policy *policy __free(put_cpufreq_policy) = NULL;
 		struct amd_cpudata *cpudata;
+		union perf_cached perf;
 
 		policy = cpufreq_cpu_get(cpu);
 		if (!policy)
 			continue;
+
 		cpudata = policy->driver_data;
+		perf = READ_ONCE(cpudata->perf);
 
 		if (!((policy->cpuinfo.max_freq >= cpudata->nominal_freq) &&
 			(cpudata->nominal_freq > cpudata->lowest_nonlinear_freq) &&
@@ -242,7 +245,25 @@ static int amd_pstate_ut_check_freq(u32 index)
 			return -EINVAL;
 		}
 
-		if (cpudata->lowest_nonlinear_freq != policy->min) {
+		if (perf.bios_min_perf) {
+			u32 bios_min_freq = perf_to_freq(perf, cpudata->nominal_freq,
+							 perf.bios_min_perf);
+
+			/*
+			 * User set bios_min_freq cannot be trusted to
+			 * be within the driver limits. Clamp it similar
+			 * to cpufreq_verify_within_cpu_limits().
+			 */
+			bios_min_freq = clamp_t(u32, bios_min_freq,
+						     policy->cpuinfo.min_freq,
+						     policy->cpuinfo.max_freq);
+
+			if (bios_min_freq != policy->min) {
+				pr_err("%s cpu%d bios_min_freq=%d policy_min=%d, they should be equal!\n",
+					__func__, cpu, bios_min_freq, policy->min);
+				return -EINVAL;
+			}
+		} else if (cpudata->lowest_nonlinear_freq != policy->min) {
 			pr_err("%s cpu%d cpudata_lowest_nonlinear_freq=%d policy_min=%d, they should be equal!\n",
 				__func__, cpu, cpudata->lowest_nonlinear_freq, policy->min);
 			return -EINVAL;
diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index 8bfd46d60843..ae1673b36ac4 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -145,19 +145,6 @@ static struct quirk_entry quirk_amd_7k62 = {
 	.lowest_freq = 550,
 };
 
-static inline u8 freq_to_perf(union perf_cached perf, u32 nominal_freq, unsigned int freq_val)
-{
-	u32 perf_val = DIV_ROUND_UP_ULL((u64)freq_val * perf.nominal_perf, nominal_freq);
-
-	return (u8)clamp(perf_val, perf.lowest_perf, perf.highest_perf);
-}
-
-static inline u32 perf_to_freq(union perf_cached perf, u32 nominal_freq, u8 perf_val)
-{
-	return DIV_ROUND_UP_ULL((u64)nominal_freq * perf_val,
-				perf.nominal_perf);
-}
-
 static int __init dmi_matched_7k62_bios_bug(const struct dmi_system_id *dmi)
 {
 	/**
diff --git a/drivers/cpufreq/amd-pstate.h b/drivers/cpufreq/amd-pstate.h
index 9f5a81976eae..578465187b7a 100644
--- a/drivers/cpufreq/amd-pstate.h
+++ b/drivers/cpufreq/amd-pstate.h
@@ -159,6 +159,20 @@ enum amd_pstate_mode {
 	AMD_PSTATE_GUIDED,
 	AMD_PSTATE_MAX,
 };
+
+static inline u8 freq_to_perf(union perf_cached perf, u32 nominal_freq, unsigned int freq_val)
+{
+	u32 perf_val = DIV_ROUND_UP_ULL((u64)freq_val * perf.nominal_perf, nominal_freq);
+
+	return (u8)clamp(perf_val, perf.lowest_perf, perf.highest_perf);
+}
+
+static inline u32 perf_to_freq(union perf_cached perf, u32 nominal_freq, u8 perf_val)
+{
+	return DIV_ROUND_UP_ULL((u64)nominal_freq * perf_val,
+				perf.nominal_perf);
+}
+
 const char *amd_pstate_get_mode_string(enum amd_pstate_mode mode);
 int amd_pstate_get_status(void);
 int amd_pstate_update_status(const char *buf, size_t size);