On Fri, 20 Apr 2012 08:39:17 -0700, Guenter Roeck wrote:
> The following build warning is seen in some configurations.
>
> drivers/hwmon/ad7314.c: In function 'ad7314_show_temperature':
> drivers/hwmon/ad7314.c:70: warning: 'data' may be used uninitialized in this function
>
> Fix by overloading the return value from ad7314_spi_read with both data and
> error code (the returned data is really u16 and needs to be converted into a
> signed value anyway).
>
> Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> Cc: Jonathan Cameron <jic23@xxxxxxxxx>
> ---
> drivers/hwmon/ad7314.c | 12 +++++-------
> 1 files changed, 5 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/hwmon/ad7314.c b/drivers/hwmon/ad7314.c
> index ce43642..f85ce70 100644
> --- a/drivers/hwmon/ad7314.c
> +++ b/drivers/hwmon/ad7314.c
> @@ -47,7 +47,7 @@ struct ad7314_data {
> u16 rx ____cacheline_aligned;
> };
>
> -static int ad7314_spi_read(struct ad7314_data *chip, s16 *data)
> +static int ad7314_spi_read(struct ad7314_data *chip)
> {
> int ret;
>
> @@ -57,9 +57,7 @@ static int ad7314_spi_read(struct ad7314_data *chip, s16 *data)
> return ret;
> }
>
> - *data = be16_to_cpu(chip->rx);
> -
> - return ret;
> + return be16_to_cpu(chip->rx);
> }
>
> static ssize_t ad7314_show_temperature(struct device *dev,
> @@ -70,12 +68,12 @@ static ssize_t ad7314_show_temperature(struct device *dev,
> s16 data;
> int ret;
>
> - ret = ad7314_spi_read(chip, &data);
> + ret = ad7314_spi_read(chip);
> if (ret < 0)
> return ret;
> switch (spi_get_device_id(chip->spi_dev)->driver_data) {
> case ad7314:
> - data = (data & AD7314_TEMP_MASK) >> AD7314_TEMP_OFFSET;
> + data = (ret & AD7314_TEMP_MASK) >> AD7314_TEMP_OFFSET;
> data = (data << 6) >> 6;
>
> return sprintf(buf, "%d\n", 250 * data);
> @@ -86,7 +84,7 @@ static ssize_t ad7314_show_temperature(struct device *dev,
> * with a sign bit - which is a 14 bit 2's complement
> * register. 1lsb - 31.25 milli degrees centigrade
> */
> - data &= ADT7301_TEMP_MASK;
> + data = ret & ADT7301_TEMP_MASK;
> data = (data << 2) >> 2;
>
> return sprintf(buf, "%d\n",
This change looks good:
Acked-by: Jean Delvare <khali@xxxxxxxxxxxx>
The original code looks a little weird though. Some of the defined
constants aren't used, "offset" is used where "shift" should be.
Introducing function sign_extend16 would also make the code more
readable. I'll send a patch...
--
Jean Delvare
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