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SubjectRe: [PATCH] i2c driver fixes for 2.6.4
Date
From
ChangeSet 1.1608.74.16, 2004/03/15 13:09:19-08:00, khali@linux-fr.org

[PATCH] I2C: Setting w83781d fan_div preserves fan_min

This patch makes the w83781d driver preserve fan_min settings when the
user changes fan_divs. This isn't done "by default" because the actual
fan min value (in RPMs) depends on both the fan_min register and the
fan_div register. Only two drivers handle it properly at the moment as
far as I know (lm78 and asb100). Several other drivers would need to be
fixed the same way, but well, once at a time ;)

Tested on my AS99127F rev.1.

Credits go to Philip Pokorny, since I think I remember he is the one who
introduced the method in the lm78 driver in the first place.

This tends to increase the size of the three set_store_regs_fan_div
functions, and I am considering refactoring them at some point. Later
though.


drivers/i2c/chips/w83781d.c | 37 ++++++++++++++++++++++++++++++++++---
1 files changed, 34 insertions(+), 3 deletions(-)

diff -Nru a/drivers/i2c/chips/w83781d.c b/drivers/i2c/chips/w83781d.c
--- a/drivers/i2c/chips/w83781d.c Mon Mar 15 14:33:59 2004
+++ b/drivers/i2c/chips/w83781d.c Mon Mar 15 14:33:59 2004
@@ -615,12 +615,21 @@
(long) DIV_FROM_REG(data->fan_div[nr - 1]));
}

+/* Note: we save and restore the fan minimum here, because its value is
+ determined in part by the fan divisor. This follows the principle of
+ least suprise; the user doesn't expect the fan minimum to change just
+ because the divisor changed. */
static ssize_t
store_regs_fan_div_1(struct device *dev, const char *buf, size_t count)
{
struct i2c_client *client = to_i2c_client(dev);
struct w83781d_data *data = i2c_get_clientdata(client);
- u32 reg;
+ unsigned long min;
+ u8 reg;
+
+ /* Save fan_min */
+ min = FAN_FROM_REG(data->fan_min[0],
+ DIV_FROM_REG(data->fan_div[0]));

data->fan_div[0] = DIV_TO_REG(simple_strtoul(buf, NULL, 10),
data->type);
@@ -636,6 +645,10 @@
w83781d_write_value(client, W83781D_REG_VBAT, reg);
}

+ /* Restore fan_min */
+ data->fan_min[0] = FAN_TO_REG(min, DIV_FROM_REG(data->fan_div[0]));
+ w83781d_write_value(client, W83781D_REG_FAN_MIN(1), data->fan_min[0]);
+
return count;
}

@@ -644,7 +657,12 @@
{
struct i2c_client *client = to_i2c_client(dev);
struct w83781d_data *data = i2c_get_clientdata(client);
- u32 reg;
+ unsigned long min;
+ u8 reg;
+
+ /* Save fan_min */
+ min = FAN_FROM_REG(data->fan_min[1],
+ DIV_FROM_REG(data->fan_div[1]));

data->fan_div[1] = DIV_TO_REG(simple_strtoul(buf, NULL, 10),
data->type);
@@ -660,6 +678,10 @@
w83781d_write_value(client, W83781D_REG_VBAT, reg);
}

+ /* Restore fan_min */
+ data->fan_min[1] = FAN_TO_REG(min, DIV_FROM_REG(data->fan_div[1]));
+ w83781d_write_value(client, W83781D_REG_FAN_MIN(2), data->fan_min[1]);
+
return count;
}

@@ -668,7 +690,12 @@
{
struct i2c_client *client = to_i2c_client(dev);
struct w83781d_data *data = i2c_get_clientdata(client);
- u32 reg;
+ unsigned long min;
+ u8 reg;
+
+ /* Save fan_min */
+ min = FAN_FROM_REG(data->fan_min[2],
+ DIV_FROM_REG(data->fan_div[2]));

data->fan_div[2] = DIV_TO_REG(simple_strtoul(buf, NULL, 10),
data->type);
@@ -683,6 +710,10 @@
reg |= (data->fan_div[2] & 0x04) << 5;
w83781d_write_value(client, W83781D_REG_VBAT, reg);
}
+
+ /* Restore fan_min */
+ data->fan_min[2] = FAN_TO_REG(min, DIV_FROM_REG(data->fan_div[2]));
+ w83781d_write_value(client, W83781D_REG_FAN_MIN(3), data->fan_min[2]);

return count;
}
-
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