[i2c] [PATCH] i2c/tsl2550: Speed up initialization

[Jean Delvare]

Hi Rodolfo,

There's some redundancy in the tsl2550 initialization sequence. It is
powering up the device twice, and setting the operating mode twice
too. Setting things just once saves SMBus transactions, which aren't
always cheap, speeding up the device initialization.

Signed-off-by: Jean Delvare <khali at linux-fr.org>
---
 drivers/i2c/chips/tsl2550.c |   46 ++++++++++++++++++++++++-------------------
 1 file changed, 26 insertions(+), 20 deletions(-)

--- linux-2.6.22-rc5.orig/drivers/i2c/chips/tsl2550.c	2007-06-23 11:26:08.000000000 +0200
+++ linux-2.6.22-rc5/drivers/i2c/chips/tsl2550.c	2007-06-23 11:28:54.000000000 +0200
@@ -27,7 +27,7 @@
 #include <linux/delay.h>
 
 #define TSL2550_DRV_NAME	"tsl2550"
-#define DRIVER_VERSION		"1.1.0"
+#define DRIVER_VERSION		"1.1.1"
 
 /*
  * Defines
@@ -333,13 +333,30 @@ static const struct attribute_group tsl2
  * Initialization function
  */
 
-static void tsl2550_init_client(struct i2c_client *client)
+static int tsl2550_init_client(struct i2c_client *client)
 {
 	struct tsl2550_data *data = i2c_get_clientdata(client);
+	int err;
 
-	/* Power up the device and set the default operating mode */
-	tsl2550_set_power_state(client, 1);
-	tsl2550_set_operating_mode(client, data->operating_mode);
+	/*
+	 * Probe the chip. To do so we try to power up the device and then to
+	 * read back the 0x03 code
+	 */
+	err = i2c_smbus_write_byte(client, TSL2550_POWER_UP);
+	if (err < 0)
+		return err;
+	mdelay(1);
+	if (i2c_smbus_read_byte(client) != TSL2550_POWER_UP)
+		return -ENODEV;
+	data->power_state = 1;
+
+	/* Set the default operating mode */
+	err = i2c_smbus_write_byte(client,
+				   TSL2550_MODE_RANGE[data->operating_mode]);
+	if (err < 0)
+		return err;
+
+	return 0;
 }
 
 /*
@@ -381,24 +398,12 @@ static int __devinit tsl2550_probe(struc
 	dev_info(&client->dev, "%s operating mode\n",
 			data->operating_mode ? "extended" : "standard");
 
-	/*
-	 * Probe the chip. To do so we try to power up the device and then to
-	 * read back the 0x03 code
-	 */
-	err = i2c_smbus_write_byte(client, TSL2550_POWER_UP);
-	if (err < 0)
-		goto exit_kfree;
-	mdelay(1);
-	err = i2c_smbus_read_byte(client);
-	if (err != TSL2550_POWER_UP) {
-		err = -ENODEV;
-		goto exit_kfree;
-	}
-
 	mutex_init(&data->update_lock);
 
 	/* Initialize the TSL2550 chip */
-	tsl2550_init_client(client);
+	err = tsl2550_init_client(client);
+	if (err)
+		goto exit_kfree;
 
 	/* Register sysfs hooks */
 	err = sysfs_create_group(&client->dev.kobj, &tsl2550_attr_group);
@@ -449,6 +454,7 @@ static void __exit tsl2550_exit(void)
 MODULE_AUTHOR("Rodolfo Giometti <giometti at linux.it>");
 MODULE_DESCRIPTION("TSL2550 ambient light sensor driver");
 MODULE_LICENSE("GPL");
+MODULE_VERSION(DRIVER_VERSION);
 
 module_init(tsl2550_init);
 module_exit(tsl2550_exit);


-- 
Jean Delvare