1 files changed, 21 insertions, 6 deletions

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index 5ab6a4fe93aa..75a5408e6981 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -2476,6 +2476,7 @@ static bool __init intel_pstate_no_acpi_pss(void)
 		kfree(pss);
 	}
 
+	pr_debug("ACPI _PSS not found\n");
 	return true;
 }
 
@@ -2486,9 +2487,14 @@ static bool __init intel_pstate_no_acpi_pcch(void)
 
 	status = acpi_get_handle(NULL, "\\_SB", &handle);
 	if (ACPI_FAILURE(status))
-		return true;
+		goto not_found;
+
+	if (acpi_has_method(handle, "PCCH"))
+		return false;
 
-	return !acpi_has_method(handle, "PCCH");
+not_found:
+	pr_debug("ACPI PCCH not found\n");
+	return true;
 }
 
 static bool __init intel_pstate_has_acpi_ppc(void)
@@ -2503,6 +2509,7 @@ static bool __init intel_pstate_has_acpi_ppc(void)
 		if (acpi_has_method(pr->handle, "_PPC"))
 			return true;
 	}
+	pr_debug("ACPI _PPC not found\n");
 	return false;
 }
 
@@ -2540,8 +2547,10 @@ static bool __init intel_pstate_platform_pwr_mgmt_exists(void)
 	id = x86_match_cpu(intel_pstate_cpu_oob_ids);
 	if (id) {
 		rdmsrl(MSR_MISC_PWR_MGMT, misc_pwr);
-		if ( misc_pwr & (1 << 8))
+		if (misc_pwr & (1 << 8)) {
+			pr_debug("Bit 8 in the MISC_PWR_MGMT MSR set\n");
 			return true;
+		}
 	}
 
 	idx = acpi_match_platform_list(plat_info);
@@ -2607,22 +2616,28 @@ static int __init intel_pstate_init(void)
 		}
 	} else {
 		id = x86_match_cpu(intel_pstate_cpu_ids);
-		if (!id)
+		if (!id) {
+			pr_info("CPU ID not supported\n");
 			return -ENODEV;
+		}
 
 		copy_cpu_funcs((struct pstate_funcs *)id->driver_data);
 	}
 
-	if (intel_pstate_msrs_not_valid())
+	if (intel_pstate_msrs_not_valid()) {
+		pr_info("Invalid MSRs\n");
 		return -ENODEV;
+	}
 
 hwp_cpu_matched:
 	/*
 	 * The Intel pstate driver will be ignored if the platform
 	 * firmware has its own power management modes.
 	 */
-	if (intel_pstate_platform_pwr_mgmt_exists())
+	if (intel_pstate_platform_pwr_mgmt_exists()) {
+		pr_info("P-states controlled by the platform\n");
 		return -ENODEV;
+	}
 
 	if (!hwp_active && hwp_only)
 		return -ENOTSUPP;