[PATCH] rtc: pcf85063: preserve control register value between stop and start

[PATCH] rtc: pcf85063: preserve control register value between stop and start

[Alvin Šipraga]

Fix a bug that caused the Control_1 register to get zeroed whenever the
RTC time is set. The problem occurred between stopping and starting the
RTC clock, wherein the return value of a successful I2C write function
would get written to the register.

Also update variables of the start and stop functions to be more
consistent with the rest of the driver.

Signed-off-by: Alvin Šipraga <alvin@airtame.com>
---
 drivers/rtc/rtc-pcf85063.c | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/drivers/rtc/rtc-pcf85063.c b/drivers/rtc/rtc-pcf85063.c
index 49bcbb3d4a69..283c2335b01b 100644
--- a/drivers/rtc/rtc-pcf85063.c
+++ b/drivers/rtc/rtc-pcf85063.c
@@ -43,37 +43,38 @@ static struct i2c_driver pcf85063_driver;
 
 static int pcf85063_stop_clock(struct i2c_client *client, u8 *ctrl1)
 {
-	s32 ret;
+	int rc;
+	u8 reg;
 
-	ret = i2c_smbus_read_byte_data(client, PCF85063_REG_CTRL1);
-	if (ret < 0) {
+	rc = i2c_smbus_read_byte_data(client, PCF85063_REG_CTRL1);
+	if (rc < 0) {
 		dev_err(&client->dev, "Failing to stop the clock\n");
 		return -EIO;
 	}
 
 	/* stop the clock */
-	ret |= PCF85063_REG_CTRL1_STOP;
+	reg = rc | PCF85063_REG_CTRL1_STOP;
 
-	ret = i2c_smbus_write_byte_data(client, PCF85063_REG_CTRL1, ret);
-	if (ret < 0) {
+	rc = i2c_smbus_write_byte_data(client, PCF85063_REG_CTRL1, reg);
+	if (rc < 0) {
 		dev_err(&client->dev, "Failing to stop the clock\n");
 		return -EIO;
 	}
 
-	*ctrl1 = ret;
+	*ctrl1 = reg;
 
 	return 0;
 }
 
 static int pcf85063_start_clock(struct i2c_client *client, u8 ctrl1)
 {
-	s32 ret;
+	int rc;
 
 	/* start the clock */
 	ctrl1 &= ~PCF85063_REG_CTRL1_STOP;
 
-	ret = i2c_smbus_write_byte_data(client, PCF85063_REG_CTRL1, ctrl1);
-	if (ret < 0) {
+	rc = i2c_smbus_write_byte_data(client, PCF85063_REG_CTRL1, ctrl1);
+	if (rc < 0) {
 		dev_err(&client->dev, "Failing to start the clock\n");
 		return -EIO;
 	}
-- 
2.11.0

Re: [PATCH] rtc: pcf85063: preserve control register value between stop and start

[Alexandre Belloni]

On 15/07/2018 23:31:53+0200, Alvin Šipraga wrote:
> Fix a bug that caused the Control_1 register to get zeroed whenever the
> RTC time is set. The problem occurred between stopping and starting the
> RTC clock, wherein the return value of a successful I2C write function
> would get written to the register.
> 
> Also update variables of the start and stop functions to be more
> consistent with the rest of the driver.
> 
> Signed-off-by: Alvin Šipraga <alvin@airtame.com>
> ---
>  drivers/rtc/rtc-pcf85063.c | 21 +++++++++++----------
>  1 file changed, 11 insertions(+), 10 deletions(-)
> 

Applied, thanks.

-- 
Alexandre Belloni, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com