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-rw-r--r--drivers/hwmon/dell-smm-hwmon.c40
1 files changed, 39 insertions, 1 deletions
diff --git a/drivers/hwmon/dell-smm-hwmon.c b/drivers/hwmon/dell-smm-hwmon.c
index aef4f8317ae2..3f8b4e482b64 100644
--- a/drivers/hwmon/dell-smm-hwmon.c
+++ b/drivers/hwmon/dell-smm-hwmon.c
@@ -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)