Re: 2.6.10-mm2: it87 sensor driver stops CPU fan

Jonas Munsin
2005-01-12T22:32:53Z

> 2* I would then add a check to the it87 driver, which completely disables
> the fan speed control interface if the initial configuration looks weird
> (all fans supposedly stopped and polarity set to "active low"). This
> should protect users of the driver who have a faulty BIOS.
>
> When a bogus configuration is detected, we would of course complain in
> the logs and invite the user to complain to his/her motherboard maker
> too.

Here is it87.c_2.6.10-jm4-detect_broken_bios_20050112.diff implementing
this. It goes on top of the previous patch.

- detects broken bioses, disables the pwm for them and prints a message
- fixes an unrelated minor bug in set_fan_div()

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Jonas Munsin <jmunsin@iki.fi>

--- linux-2.6.10/drivers/i2c/chips/it87.c 2005-01-12 23:58:51.000000000 +0200
+++ linux-2.6.10/drivers/i2c/chips/it87.c_2.6.10-jm4-detect_broken_bios_20050112 2005-01-12 23:58:34.000000000 +0200
@@ -500,7 +500,7 @@ static ssize_t set_fan_div(struct device
else
data->fan_div[nr] = 3;
}
- val = old & 0x100;
+ val = old & 0x80;
val |= (data->fan_div[0] & 0x07);
val |= (data->fan_div[1] & 0x07) << 3;
if (data->fan_div[2] == 3)
@@ -703,6 +703,8 @@ int it87_detect(struct i2c_adapter *adap
int err = 0;
const char *name = "";
int is_isa = i2c_is_isa_adapter(adapter);
+ int enable_pwm_interface;
+ int tmp;

if (!is_isa &&
!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
@@ -812,6 +814,17 @@ int it87_detect(struct i2c_adapter *adap
/* Initialize the IT87 chip */
it87_init_client(new_client, data);

+ /* Some BIOSes fail to correctly configure the IT87 fans. All fans off
+ * and polarity set to active low is sign that this is the case so we
+ * disable pwm control to protect the user. */
+ enable_pwm_interface = 1;
+ tmp = it87_read_value(new_client, IT87_REG_FAN_CTL);
+ if ((tmp & 0x87) == 0) {
+ enable_pwm_interface = 0;
+ dev_info(&new_client->dev,
+ "detected broken BIOS defaults, disabling pwm interface");
+ }
+
/* Register sysfs hooks */
device_create_file(&new_client->dev, &dev_attr_in0_input);
device_create_file(&new_client->dev, &dev_attr_in1_input);
@@ -860,12 +873,14 @@ int it87_detect(struct i2c_adapter *adap
device_create_file(&new_client->dev, &dev_attr_fan2_div);
device_create_file(&new_client->dev, &dev_attr_fan3_div);
device_create_file(&new_client->dev, &dev_attr_alarms);
- device_create_file(&new_client->dev, &dev_attr_pwm1_enable);
- device_create_file(&new_client->dev, &dev_attr_pwm2_enable);
- device_create_file(&new_client->dev, &dev_attr_pwm3_enable);
- device_create_file(&new_client->dev, &dev_attr_pwm1);
- device_create_file(&new_client->dev, &dev_attr_pwm2);
- device_create_file(&new_client->dev, &dev_attr_pwm3);
+ if (enable_pwm_interface) {
+ device_create_file(&new_client->dev, &dev_attr_pwm1_enable);
+ device_create_file(&new_client->dev, &dev_attr_pwm2_enable);
+ device_create_file(&new_client->dev, &dev_attr_pwm3_enable);
+ device_create_file(&new_client->dev, &dev_attr_pwm1);
+ device_create_file(&new_client->dev, &dev_attr_pwm2);
+ device_create_file(&new_client->dev, &dev_attr_pwm3);
+ }

if (data->type == it8712) {
device_create_file_vrm(new_client);