Commit 2744d2fd authored by Pali Rohár's avatar Pali Rohár Committed by Guenter Roeck
Browse files

hwmon: (dell-smm) Disallow fan_type() calls on broken machines 



Some Dell machines have especially broken SMM or BIOS which cause that once
fan_type() is called then CPU fan speed going randomly up and down. And for
fixing this behaviour reboot is required.

So this patch creates fan_type blacklist of affected Dell machines and
disallow fan_type() call on them to prevent that erratic behaviour.

Old blacklist which disabled loading driver on some machines added in
commits a4b45b25 ("hwmon: (dell-smm) Blacklist Dell Studio XPS 8100")
and 6220f4eb ("hwmon: (dell-smm) Blacklist Dell Studio XPS 8000") were
moved to FAN_TYPE blacklist.

Reported-by: default avatarJan C Peters <jcpeters89@gmail.com>
Signed-off-by: default avatarPali Rohár <pali.rohar@gmail.com>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=100121


Cc: stable@vger.kernel.org # v4.0+, will need backport
Signed-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
parent 7613663c

drivers/hwmon/dell-smm-hwmon.c

+25 −11
Original line number Diff line number Diff line
@@ -73,6 +73,7 @@ static u32 i8k_hwmon_flags; 
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;



#define I8K_HWMON_HAVE_TEMP1	(1 << 0)

#define I8K_HWMON_HAVE_TEMP2	(1 << 1)
@@ -241,6 +242,9 @@ static int i8k_get_fan_type(int fan) 
{

	struct smm_regs regs = { .eax = I8K_SMM_GET_FAN_TYPE, };



	if (disallow_fan_type_call)

		return -EINVAL;



	regs.ebx = fan & 0xff;

	return i8k_smm(&regs) ? : regs.eax & 0xff;

}
@@ -726,6 +730,9 @@ static struct attribute *i8k_attrs[] = { 
static umode_t i8k_is_visible(struct kobject *kobj, struct attribute *attr,

			      int index)

{

	if (disallow_fan_type_call &&

	    (index == 9 || index == 12))

		return 0;

	if (index >= 0 && index <= 1 &&

	    !(i8k_hwmon_flags & I8K_HWMON_HAVE_TEMP1))

		return 0;
@@ -937,12 +944,14 @@ static struct dmi_system_id i8k_dmi_table[] __initdata = { 


MODULE_DEVICE_TABLE(dmi, i8k_dmi_table);



static struct dmi_system_id i8k_blacklist_dmi_table[] __initdata = {

	{

/*

		 * CPU fan speed going up and down on Dell Studio XPS 8000

		 * for unknown reasons.

 * On some machines once I8K_SMM_GET_FAN_TYPE is issued then CPU fan speed

 * randomly going up and down due to bug in Dell SMM or BIOS. Here is blacklist

 * of affected Dell machines for which we disallow I8K_SMM_GET_FAN_TYPE call.

 * See bug: https://bugzilla.kernel.org/show_bug.cgi?id=100121

 */

static struct dmi_system_id i8k_blacklist_fan_type_dmi_table[] __initdata = {

	{

		.ident = "Dell Studio XPS 8000",

		.matches = {

			DMI_EXACT_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
@@ -950,16 +959,19 @@ static struct dmi_system_id i8k_blacklist_dmi_table[] __initdata = { 
		},

	},

	{

		/*

		 * CPU fan speed going up and down on Dell Studio XPS 8100

		 * for unknown reasons.

		 */

		.ident = "Dell Studio XPS 8100",

		.matches = {

			DMI_EXACT_MATCH(DMI_SYS_VENDOR, "Dell Inc."),

			DMI_EXACT_MATCH(DMI_PRODUCT_NAME, "Studio XPS 8100"),

		},

	},

	{

		.ident = "Dell Inspiron 580",

		.matches = {

			DMI_EXACT_MATCH(DMI_SYS_VENDOR, "Dell Inc."),

			DMI_EXACT_MATCH(DMI_PRODUCT_NAME, "Inspiron 580 "),

		},

	},

	{ }

};
@@ -974,8 +986,7 @@ static int __init i8k_probe(void) 
	/*

	 * Get DMI information

	 */

	if (!dmi_check_system(i8k_dmi_table) ||

	    dmi_check_system(i8k_blacklist_dmi_table)) {

	if (!dmi_check_system(i8k_dmi_table)) {

		if (!ignore_dmi && !force)

			return -ENODEV;
@@ -986,6 +997,9 @@ 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;



	strlcpy(bios_version, i8k_get_dmi_data(DMI_BIOS_VERSION),

		sizeof(bios_version));

	strlcpy(bios_machineid, i8k_get_dmi_data(DMI_PRODUCT_SERIAL),

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