[PATCH] cpufreq: intel_pstate: Override parameters if HWP forced by BIOS

From: Doug Smythies <doug.smythies@gmail.com>
To: srinivas.pandruvada@linux.intel.com, rafael@kernel.org,
	len.brown@intel.com
Cc: dsmythies@telus.net, linux-kernel@vger.kernel.org,
	linux-pm@vger.kernel.org
Subject: [PATCH] cpufreq: intel_pstate: Override parameters if HWP forced by BIOS
Date: Wed,  8 Sep 2021 20:48:02 -0700	[thread overview]
Message-ID: <20210909034802.1708-1-dsmythies@telus.net> (raw)

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.

Signed-off-by: Doug Smythies <dsmythies@telus.net>
---
 drivers/cpufreq/intel_pstate.c | 22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index bb4549959b11..073bae5d4498 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -3267,7 +3267,7 @@ static int __init intel_pstate_init(void)
 		 */
 		if ((!no_hwp && boot_cpu_has(X86_FEATURE_HWP_EPP)) ||
 		    intel_pstate_hwp_is_enabled()) {
-			hwp_active++;
+			hwp_active = 1;
 			hwp_mode_bdw = id->driver_data;
 			intel_pstate.attr = hwp_cpufreq_attrs;
 			intel_cpufreq.attr = hwp_cpufreq_attrs;
@@ -3347,17 +3347,27 @@ device_initcall(intel_pstate_init);
 
 static int __init intel_pstate_setup(char *str)
 {
+	/*
+	 * If BIOS is forcing HWP, then parameter
+	 * overrides might be needed. Only print
+	 * the message once, and regardless of
+	 * any overrides.
+	 */
+	if(!hwp_active && boot_cpu_has(X86_FEATURE_HWP))
+		if(intel_pstate_hwp_is_enabled()){
+			pr_info("HWP enabled by BIOS\n");
+			hwp_active = 1;
+		}
 	if (!str)
 		return -EINVAL;
 
-	if (!strcmp(str, "disable"))
+	if (!strcmp(str, "disable") && !hwp_active)
 		no_load = 1;
-	else if (!strcmp(str, "active"))
+	if (!strcmp(str, "active"))
 		default_driver = &intel_pstate;
-	else if (!strcmp(str, "passive"))
+	if (!strcmp(str, "passive"))
 		default_driver = &intel_cpufreq;
-
-	if (!strcmp(str, "no_hwp")) {
+	if (!strcmp(str, "no_hwp") && !hwp_active) {
 		pr_info("HWP disabled\n");
 		no_hwp = 1;
 	}
-- 
2.25.1

