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authorDarrick J. Wong <djwong@us.ibm.com>2009-01-06 14:41:32 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2009-01-06 15:59:18 -0800
commit2e75a4b7ae0dd4bf7b34e41c2c3be7ac23b8f1cc (patch)
tree3adaaa6a78b2d11b7648a93956c10a0968abd09c /drivers
parent8f8c1fb0c829278b889588da211a5a557518b06c (diff)
downloadlinux-2.6.34-ux500-2e75a4b7ae0dd4bf7b34e41c2c3be7ac23b8f1cc.tar.gz
adt7470: fix pwm at a certain level during temperature sensor scan
In the small window that it takes to read the temperature sensors, the pwm outputs momentarily drop to 0. This causes a noticeable hiccup in fan speed, which is slightly annoying. The solution is to manually program the pwm output with whatever the automatic value is and then shift the fans to manual control while reading temperatures. Once that is done, put the fans back to whatever mode of control was there before. Signed-off-by: Darrick J. Wong <djwong@us.ibm.com> Cc: Jean Delvare <khali@linux-fr.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/hwmon/adt7470.c25
1 files changed, 24 insertions, 1 deletions
diff --git a/drivers/hwmon/adt7470.c b/drivers/hwmon/adt7470.c
index da6c9306ca5..b7a442a80bd 100644
--- a/drivers/hwmon/adt7470.c
+++ b/drivers/hwmon/adt7470.c
@@ -74,6 +74,7 @@ I2C_CLIENT_INSMOD_1(adt7470);
#define ADT7470_REG_PWM12_CFG 0x68
#define ADT7470_PWM2_AUTO_MASK 0x40
#define ADT7470_PWM1_AUTO_MASK 0x80
+#define ADT7470_PWM_AUTO_MASK 0xC0
#define ADT7470_REG_PWM34_CFG 0x69
#define ADT7470_PWM3_AUTO_MASK 0x40
#define ADT7470_PWM4_AUTO_MASK 0x80
@@ -223,7 +224,7 @@ static struct adt7470_data *adt7470_update_device(struct device *dev)
struct i2c_client *client = to_i2c_client(dev);
struct adt7470_data *data = i2c_get_clientdata(client);
unsigned long local_jiffies = jiffies;
- u8 cfg;
+ u8 cfg, pwm[4], pwm_cfg[2];
int i;
mutex_lock(&data->lock);
@@ -232,6 +233,24 @@ static struct adt7470_data *adt7470_update_device(struct device *dev)
&& data->sensors_valid)
goto no_sensor_update;
+ /* save pwm[1-4] config register */
+ pwm_cfg[0] = i2c_smbus_read_byte_data(client, ADT7470_REG_PWM_CFG(0));
+ pwm_cfg[1] = i2c_smbus_read_byte_data(client, ADT7470_REG_PWM_CFG(2));
+
+ /* set manual pwm to whatever it is set to now */
+ for (i = 0; i < ADT7470_FAN_COUNT; i++)
+ pwm[i] = i2c_smbus_read_byte_data(client, ADT7470_REG_PWM(i));
+
+ /* put pwm in manual mode */
+ i2c_smbus_write_byte_data(client, ADT7470_REG_PWM_CFG(0),
+ pwm_cfg[0] & ~(ADT7470_PWM_AUTO_MASK));
+ i2c_smbus_write_byte_data(client, ADT7470_REG_PWM_CFG(2),
+ pwm_cfg[1] & ~(ADT7470_PWM_AUTO_MASK));
+
+ /* write pwm control to whatever it was */
+ for (i = 0; i < ADT7470_FAN_COUNT; i++)
+ i2c_smbus_write_byte_data(client, ADT7470_REG_PWM(i), pwm[i]);
+
/* start reading temperature sensors */
cfg = i2c_smbus_read_byte_data(client, ADT7470_REG_CFG);
cfg |= 0x80;
@@ -249,6 +268,10 @@ static struct adt7470_data *adt7470_update_device(struct device *dev)
cfg &= ~0x80;
i2c_smbus_write_byte_data(client, ADT7470_REG_CFG, cfg);
+ /* restore pwm[1-4] config registers */
+ i2c_smbus_write_byte_data(client, ADT7470_REG_PWM_CFG(0), pwm_cfg[0]);
+ i2c_smbus_write_byte_data(client, ADT7470_REG_PWM_CFG(2), pwm_cfg[1]);
+
for (i = 0; i < ADT7470_TEMP_COUNT; i++)
data->temp[i] = i2c_smbus_read_byte_data(client,
ADT7470_TEMP_REG(i));