From 076b862c7e4409d2dcacfda19f7eaf8d07ab9200 Mon Sep 17 00:00:00 2001 From: Erwan Velu Date: Wed, 13 Feb 2019 09:58:35 +0100 Subject: [PATCH] cpufreq: intel_pstate: Add reasons for failure and debug messages The init code path has several exceptions where the driver can decide not to load. As CONFIG_X86_INTEL_PSTATE is generally set to Y, the return code is not reachable. The initialization code is neither verbose of the reason why it did choose to prematurely exit, so it is difficult for a user to determine, on a given platform, why the driver didn't load properly. This patch is about reporting to the user the reason/context of why the driver failed to load. That is a precious hint when debugging a platform. Signed-off-by: Erwan Velu [ rjw: Subject & changelog, minor fixups ] Signed-off-by: Rafael J. Wysocki --- drivers/cpufreq/intel_pstate.c | 27 +++++++++++++++++++++------ 1 file changed, 21 insertions(+), 6 deletions(-) diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c index 5ab6a4f..75a5408 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; -- 2.7.4