[PATCH] cpufreq: intel_pstate: Add DMI quirk for Dell Inspiron systems

[Joe Walter <joe.walter@codesensesolutions.com>]

Some Dell Inspiron systems experience frequency scaling issues with
intel_pstate driver where the CPU gets locked at 900MHz after load.

Add DMI quirk table to detect affected Dell Inspiron models and prevent
intel_pstate from loading, allowing acpi-cpufreq to handle frequency
scaling instead.

Affected models:
- Dell Inspiron 15 7000 Gaming
- Dell Inspiron 7567
- Dell Inspiron 7559

Tested-by: Joe Walter <joe.walter@codesensesolutions.com>
Signed-off-by: Joe Walter <joe.walter@codesensesolutions.com>
---
 drivers/cpufreq/intel_pstate.c | 65 ++++++++++++++++++++++------------
 1 file changed, 42 insertions(+), 23 deletions(-)

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index 1b1f62ccec92..3aeb04755afa 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -28,7 +28,6 @@
 #include <linux/pm_qos.h>
 #include <linux/bitfield.h>
 #include <trace/events/power.h>
-#include <linux/dmi.h>
 #include <linux/units.h>
 
 #include <asm/cpu.h>
@@ -48,6 +47,7 @@
 #ifdef CONFIG_ACPI
 #include <acpi/processor.h>
 #include <acpi/cppc_acpi.h>
+#include <linux/dmi.h>
 #endif
 
 #define FRAC_BITS 8
@@ -299,25 +299,6 @@ struct pstate_funcs {
 
 static struct pstate_funcs pstate_funcs __read_mostly;
 
-/* DMI quirk table for systems that should prefer acpi-cpufreq over intel_pstate */
-static int intel_pstate_prefer_acpi_cpufreq(const struct dmi_system_id *id)
-{
-	pr_info("Preferring acpi-cpufreq for %s due to performance issues with intel_pstate\n",
-		id->ident);
-	return 1;
-}
-
-static const struct dmi_system_id intel_pstate_acpi_cpufreq_prefer[] = {
-	{
-		.callback = intel_pstate_prefer_acpi_cpufreq,
-		.ident = "Dell Inspiron 15 7000 Gaming",
-		.matches = {
-			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
-			DMI_MATCH(DMI_PRODUCT_NAME, "Inspiron 15 7000 Gaming"),
-		},
-	},
-	{ }
-};
 static bool hwp_active __ro_after_init;
 static int hwp_mode_bdw __ro_after_init;
 static bool per_cpu_limits __ro_after_init;
@@ -2799,6 +2780,41 @@ static const struct x86_cpu_id intel_pstate_cpu_ids[] = {
 };
 MODULE_DEVICE_TABLE(x86cpu, intel_pstate_cpu_ids);
 
+/* DMI quirk table for systems that should prefer acpi-cpufreq over intel_pstate */
+static int intel_pstate_prefer_acpi_cpufreq(const struct dmi_system_id *id)
+{
+	pr_info("Detected %s, preferring acpi-cpufreq\n", id->ident);
+	return 0;
+}
+
+static const struct dmi_system_id intel_pstate_acpi_cpufreq_prefer[] = {
+	{
+		.ident = "Dell Inspiron 15 7000 Gaming",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
+			DMI_MATCH(DMI_PRODUCT_NAME, "Inspiron 15 7000 Gaming"),
+		},
+		.callback = intel_pstate_prefer_acpi_cpufreq,
+	},
+	{
+		.ident = "Dell Inspiron 7567",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
+			DMI_MATCH(DMI_PRODUCT_NAME, "Inspiron 7567"),
+		},
+		.callback = intel_pstate_prefer_acpi_cpufreq,
+	},
+	{
+		.ident = "Dell Inspiron 7559",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
+			DMI_MATCH(DMI_PRODUCT_NAME, "Inspiron 7559"),
+		},
+		.callback = intel_pstate_prefer_acpi_cpufreq,
+	},
+	{}
+};
+
 #ifdef CONFIG_ACPI
 static const struct x86_cpu_id intel_pstate_cpu_oob_ids[] __initconst = {
 	X86_MATCH(INTEL_BROADWELL_D,		core_funcs),
@@ -3825,6 +3841,12 @@ static int __init intel_pstate_init(void)
 	const struct x86_cpu_id *id;
 	int rc;
 
+
+	/* Early DMI check - prevent intel_pstate on problematic systems */
+	if (dmi_check_system(intel_pstate_acpi_cpufreq_prefer)) {
+		pr_info("intel_pstate: system prefers acpi-cpufreq, not loading\n");
+		return -ENODEV;
+	}
 	if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL)
 		return -ENODEV;
 
@@ -3887,9 +3909,6 @@ static int __init intel_pstate_init(void)
 		pr_info("Invalid MSRs\n");
 		return -ENODEV;
 	}
-/* Check for systems that should prefer acpi-cpufreq */
-	if (!default_driver && dmi_check_system(intel_pstate_acpi_cpufreq_prefer))
-		default_driver = &intel_cpufreq;
 	/* Without HWP start in the passive mode. */
 	if (!default_driver)
 		default_driver = &intel_cpufreq;
-- 
2.48.1