hwmon: (dell-smm) Disable fan support on Inspiron 7720 and Vostro 3360

index c7c9e95e58a8..aef4f8317ae2 100644
@@ -1060,8 +1060,11 @@ static int __init i8k_probe(void)
 			i8k_get_dmi_data(DMI_BIOS_VERSION));
 	}
 
-	if (dmi_check_system(i8k_blacklist_fan_type_dmi_table))
-		disallow_fan_type_call = true;
+	if (dmi_check_system(i8k_blacklist_fan_type_dmi_table)) {
+		pr_warn("broken Dell BIOS detected, disallow fan type call\n");
+		if (!force)
+			disallow_fan_type_call = true;
+	}
 
 	strlcpy(bios_version, i8k_get_dmi_data(DMI_BIOS_VERSION),
 		sizeof(bios_version));

index aef4f8317ae2..3f8b4e482b64 100644
@@ -76,6 +76,7 @@ static uint i8k_fan_mult = I8K_FAN_MULT;
 static uint i8k_pwm_mult;
 static uint i8k_fan_max = I8K_FAN_HIGH;
 static bool disallow_fan_type_call;
+static bool disallow_fan_support;
 
 #define I8K_HWMON_HAVE_TEMP1	(1 << 0)
 #define I8K_HWMON_HAVE_TEMP2	(1 << 1)

@@ -242,6 +243,9 @@ static int i8k_get_fan_status(int fan)
 {
 	struct smm_regs regs = { .eax = I8K_SMM_GET_FAN, };
 
+	if (disallow_fan_support)
+		return -EINVAL;
+
 	regs.ebx = fan & 0xff;
 	return i8k_smm(&regs) ? : regs.eax & 0xff;
 }

@@ -253,6 +257,9 @@ static int i8k_get_fan_speed(int fan)
 {
 	struct smm_regs regs = { .eax = I8K_SMM_GET_SPEED, };
 
+	if (disallow_fan_support)
+		return -EINVAL;
+
 	regs.ebx = fan & 0xff;
 	return i8k_smm(&regs) ? : (regs.eax & 0xffff) * i8k_fan_mult;
 }

@@ -264,7 +271,7 @@ static int _i8k_get_fan_type(int fan)
 {
 	struct smm_regs regs = { .eax = I8K_SMM_GET_FAN_TYPE, };
 
-	if (disallow_fan_type_call)
+	if (disallow_fan_support || disallow_fan_type_call)
 		return -EINVAL;
 
 	regs.ebx = fan & 0xff;

@@ -289,6 +296,9 @@ static int i8k_get_fan_nominal_speed(int fan, int speed)
 {
 	struct smm_regs regs = { .eax = I8K_SMM_GET_NOM_SPEED, };
 
+	if (disallow_fan_support)
+		return -EINVAL;
+
 	regs.ebx = (fan & 0xff) | (speed << 8);
 	return i8k_smm(&regs) ? : (regs.eax & 0xffff) * i8k_fan_mult;
 }

@@ -300,6 +310,9 @@ static int i8k_set_fan(int fan, int speed)
 {
 	struct smm_regs regs = { .eax = I8K_SMM_SET_FAN, };
 
+	if (disallow_fan_support)
+		return -EINVAL;
+
 	speed = (speed < 0) ? 0 : ((speed > i8k_fan_max) ? i8k_fan_max : speed);
 	regs.ebx = (fan & 0xff) | (speed << 8);
 

@@ -772,6 +785,8 @@ static struct attribute *i8k_attrs[] = {
 static umode_t i8k_is_visible(struct kobject *kobj, struct attribute *attr,
 			      int index)
 {
+	if (disallow_fan_support && index >= 8)
+		return 0;
 	if (disallow_fan_type_call &&
 	    (index == 9 || index == 12 || index == 15))
 		return 0;

@@ -1039,6 +1054,23 @@ static const struct dmi_system_id i8k_blacklist_fan_type_dmi_table[] __initconst
 };
 
 /*
+ * On some machines all fan related SMM functions implemented by Dell BIOS
+ * firmware freeze kernel for about 500ms. Until Dell fixes these problems fan
+ * support for affected blacklisted Dell machines stay disabled.
+ * See bug: https://bugzilla.kernel.org/show_bug.cgi?id=195751
+ */
+static struct dmi_system_id i8k_blacklist_fan_support_dmi_table[] __initdata = {
+	{
+		.ident = "Dell Inspiron 7720",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
+			DMI_EXACT_MATCH(DMI_PRODUCT_NAME, "Inspiron 7720"),
+		},
+	},
+	{ }
+};
+
+/*
  * Probe for the presence of a supported laptop.
  */
 static int __init i8k_probe(void)

@@ -1060,6 +1092,12 @@ static int __init i8k_probe(void)
 			i8k_get_dmi_data(DMI_BIOS_VERSION));
 	}
 
+	if (dmi_check_system(i8k_blacklist_fan_support_dmi_table)) {
+		pr_warn("broken Dell BIOS detected, disallow fan support\n");
+		if (!force)
+			disallow_fan_support = true;
+	}
+
 	if (dmi_check_system(i8k_blacklist_fan_type_dmi_table)) {
 		pr_warn("broken Dell BIOS detected, disallow fan type call\n");
 		if (!force)

index 3f8b4e482b64..bf3bb7e1adab 100644
@@ -1067,6 +1067,13 @@ static struct dmi_system_id i8k_blacklist_fan_support_dmi_table[] __initdata = {
 			DMI_EXACT_MATCH(DMI_PRODUCT_NAME, "Inspiron 7720"),
 		},
 	},
+	{
+		.ident = "Dell Vostro 3360",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
+			DMI_EXACT_MATCH(DMI_PRODUCT_NAME, "Vostro 3360"),
+		},
+	},
 	{ }
 };
 

index bf3bb7e1adab..e001afd53f46 100644
@@ -147,14 +147,16 @@ static int i8k_smm_func(void *par)
 	int ebx = regs->ebx;
 	unsigned long duration;
 	ktime_t calltime, delta, rettime;
-
-	calltime = ktime_get();
 #endif
 
 	/* SMM requires CPU 0 */
 	if (smp_processor_id() != 0)
 		return -EBUSY;
 
+#ifdef DEBUG
+	calltime = ktime_get();
+#endif
+
 #if defined(CONFIG_X86_64)
 	asm volatile("pushq %%rax\n\t"
 		"movl 0(%%rax),%%edx\n\t"

@@ -208,13 +210,17 @@ static int i8k_smm_func(void *par)
 	    :    "a"(regs)
 	    :    "%ebx", "%ecx", "%edx", "%esi", "%edi", "memory");
 #endif
-	if (rc != 0 || (regs->eax & 0xffff) == 0xffff || regs->eax == eax)
-		rc = -EINVAL;
 
 #ifdef DEBUG
 	rettime = ktime_get();
 	delta = ktime_sub(rettime, calltime);
 	duration = ktime_to_ns(delta) >> 10;
+#endif
+
+	if (rc != 0 || (regs->eax & 0xffff) == 0xffff || regs->eax == eax)
+		rc = -EINVAL;
+
+#ifdef DEBUG
 	pr_debug("smm(0x%.4x 0x%.4x) = 0x%.4x  (took %7lu usecs)\n", eax, ebx,
 		(rc ? 0xffff : regs->eax & 0xffff), duration);
 #endif