linux-kernel - [34-longterm 005/247] hwmon: (via686a) Initialize fan

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Message-Id: <1308849690-14530-6-git-send-email-paul.gortmaker@windriver.com>
Date:	Thu, 23 Jun 2011 13:17:28 -0400
From:	Paul Gortmaker <paul.gortmaker@...driver.com>
To:	stable@...nel.org, linux-kernel@...r.kernel.org
Cc:	stable-review@...nel.org, Jean Delvare <khali@...ux-fr.org>,
	Paul Gortmaker <paul.gortmaker@...driver.com>
Subject: [34-longterm 005/247] hwmon: (via686a) Initialize fan_div values

From: Jean Delvare <khali@...ux-fr.org>

                   -------------------
    This is a commit scheduled for the next v2.6.34 longterm release.
    If you see a problem with using this for longterm, please comment.
                   -------------------

commit f790674d3f87df6390828ac21a7d1530f71b59c8 upstream.

Functions set_fan_min() and set_fan_div() assume that the fan_div
values have already been read from the register. The driver currently
doesn't initialize them at load time, they are only set when function
via686a_update_device() is called. This means that set_fan_min() and
set_fan_div() misbehave if, for example, "sensors -s" is called
before any monitoring application (e.g. "sensors") is has been run.

Fix the problem by always initializing the fan_div values at device
bind time.

Signed-off-by: Jean Delvare <khali@...ux-fr.org>
Acked-by: Guenter Roeck <guenter.roeck@...csson.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@...driver.com>
---
 drivers/hwmon/via686a.c |   14 +++++++++++---
 1 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/hwmon/via686a.c b/drivers/hwmon/via686a.c
index f397ce7..b2074e3 100644
--- a/drivers/hwmon/via686a.c
+++ b/drivers/hwmon/via686a.c
@@ -687,6 +687,13 @@ static int __devexit via686a_remove(struct platform_device *pdev)
 	return 0;
 }
 
+static void via686a_update_fan_div(struct via686a_data *data)
+{
+	int reg = via686a_read_value(data, VIA686A_REG_FANDIV);
+	data->fan_div[0] = (reg >> 4) & 0x03;
+	data->fan_div[1] = reg >> 6;
+}
+
 static void __devinit via686a_init_device(struct via686a_data *data)
 {
 	u8 reg;
@@ -700,6 +707,9 @@ static void __devinit via686a_init_device(struct via686a_data *data)
 	via686a_write_value(data, VIA686A_REG_TEMP_MODE,
 			    (reg & ~VIA686A_TEMP_MODE_MASK)
 			    | VIA686A_TEMP_MODE_CONTINUOUS);
+
+	/* Pre-read fan clock divisor values */
+	via686a_update_fan_div(data);
 }
 
 static struct via686a_data *via686a_update_device(struct device *dev)
@@ -751,9 +761,7 @@ static struct via686a_data *via686a_update_device(struct device *dev)
 		    (via686a_read_value(data, VIA686A_REG_TEMP_LOW23) &
 		     0xc0) >> 6;
 
-		i = via686a_read_value(data, VIA686A_REG_FANDIV);
-		data->fan_div[0] = (i >> 4) & 0x03;
-		data->fan_div[1] = i >> 6;
+		via686a_update_fan_div(data);
 		data->alarms =
 		    via686a_read_value(data,
 				       VIA686A_REG_ALARM1) |
-- 
1.7.4.4

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