cpufreq: intel_pstate: Override parameters if HWP forced by BIOS

[ Upstream commit d9a7e9df731670acdc69e81748941ad338f47fab ]

If HWP has been already been enabled by BIOS, it may be
necessary to override some kernel command line parameters.
Once it has been enabled it requires a reset to be disabled.

Suggested-by: Rafael J. Wysocki <rafael@kernel.org>
Signed-off-by: Doug Smythies <dsmythies@telus.net>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index 44a5d15a75728b18196e180397bbd0d2ec5dec76..1686705bee7bde6687f8d82e09d04650af993b56 100644 (file)
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -3035,11 +3035,15 @@ static int __init intel_pstate_init(void)
        if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL)
                return -ENODEV;
 
-       if (no_load)
-               return -ENODEV;
-
        id = x86_match_cpu(hwp_support_ids);
        if (id) {
+               bool hwp_forced = intel_pstate_hwp_is_enabled();
+
+               if (hwp_forced)
+                       pr_info("HWP enabled by BIOS\n");
+               else if (no_load)
+                       return -ENODEV;
+
                copy_cpu_funcs(&core_funcs);
                /*
                 * Avoid enabling HWP for processors without EPP support,
@@ -3049,8 +3053,7 @@ static int __init intel_pstate_init(void)
                 * If HWP is enabled already, though, there is no choice but to
                 * deal with it.
                 */
-               if ((!no_hwp && boot_cpu_has(X86_FEATURE_HWP_EPP)) ||
-                   intel_pstate_hwp_is_enabled()) {
+               if ((!no_hwp && boot_cpu_has(X86_FEATURE_HWP_EPP)) || hwp_forced) {
                        hwp_active++;
                        hwp_mode_bdw = id->driver_data;
                        intel_pstate.attr = hwp_cpufreq_attrs;
@@ -3061,7 +3064,11 @@ static int __init intel_pstate_init(void)
 
                        goto hwp_cpu_matched;
                }
+               pr_info("HWP not enabled\n");
        } else {
+               if (no_load)
+                       return -ENODEV;
+
                id = x86_match_cpu(intel_pstate_cpu_ids);
                if (!id) {
                        pr_info("CPU model not supported\n");
@@ -3138,10 +3145,9 @@ static int __init intel_pstate_setup(char *str)
        else if (!strcmp(str, "passive"))
                default_driver = &intel_cpufreq;
 
-       if (!strcmp(str, "no_hwp")) {
-               pr_info("HWP disabled\n");
+       if (!strcmp(str, "no_hwp"))
                no_hwp = 1;
-       }
+
        if (!strcmp(str, "force"))
                force_load = 1;
        if (!strcmp(str, "hwp_only"))