linux-kernel - [PATCH v3 16/16] bq27x00: Use single i2c

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Date:	Tue, 22 Feb 2011 07:38:01 +0100
From:	Lars-Peter Clausen <lars@...afoo.de>
To:	Anton Vorontsov <cbouatmailru@...il.com>
Cc:	Pali Rohar <pali.rohar@...il.com>,
	Rodolfo Giometti <giometti@...ux.it>,
	Grazvydas Ignotas <notasas@...il.com>,
	linux-kernel@...r.kernel.org, Lars-Peter Clausen <lars@...afoo.de>
Subject: [PATCH v3 16/16] bq27x00: Use single i2c_transfer call for property read

From: Grazvydas Ignotas <notasas@...il.com>

Doing this by using 2 calls sometimes results in unexpected
values being returned on OMAP3 i2c controller.

Signed-off-by: Grazvydas Ignotas <notasas@...il.com>
Signed-off-by: Lars-Peter Clausen <lars@...afoo.de>
---
 drivers/power/bq27x00_battery.c |   27 +++++++++++----------------
 1 files changed, 11 insertions(+), 16 deletions(-)

diff --git a/drivers/power/bq27x00_battery.c b/drivers/power/bq27x00_battery.c
index 740a0ac..59e68db 100644
--- a/drivers/power/bq27x00_battery.c
+++ b/drivers/power/bq27x00_battery.c
@@ -565,31 +565,26 @@ static DEFINE_MUTEX(battery_mutex);
 static int bq27x00_read_i2c(struct bq27x00_device_info *di, u8 reg, bool single)
 {
 	struct i2c_client *client = to_i2c_client(di->dev);
-	struct i2c_msg msg;
+	struct i2c_msg msg[2];
 	unsigned char data[2];
 	int ret;
 
 	if (!client->adapter)
 		return -ENODEV;
 
-	msg.addr = client->addr;
-	msg.flags = 0;
-	msg.len = 1;
-	msg.buf = data;
-
-	data[0] = reg;
-	ret = i2c_transfer(client->adapter, &msg, 1);
-
-	if (ret < 0)
-		return ret;
-
+	msg[0].addr = client->addr;
+	msg[0].flags = 0;
+	msg[0].buf = &reg;
+	msg[0].len = sizeof(reg);
+	msg[1].addr = client->addr;
+	msg[1].flags = I2C_M_RD;
+	msg[1].buf = data;
 	if (single)
-		msg.len = 1;
+		msg[1].len = 1;
 	else
-		msg.len = 2;
+		msg[1].len = 2;
 
-	msg.flags = I2C_M_RD;
-	ret = i2c_transfer(client->adapter, &msg, 1);
+	ret = i2c_transfer(client->adapter, msg, ARRAY_SIZE(msg));
 	if (ret < 0)
 		return ret;
 
-- 
1.7.2.3

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