Hi Guenter,
On Thu, 7 Jul 2011 13:42:44 -0700, Guenter Roeck wrote:
> Negative temperatures were returned in degrees C instead of milli-Degrees C.
> Also, negative temperatures were reported for remote temperature sensors even
> if the chip was configured for positive-only results.
>
> Fix by detecting temperature modes, and by treating negative temperatures
> similar to positive temperatures, with appropriate sign extension.
>
> Signed-off-by: Guenter Roeck <guenter.roeck@xxxxxxxxxxxx>
> ---
> Candidate for -stable.
>
> drivers/hwmon/lm95241.c | 20 ++++++++++++++------
> 1 files changed, 14 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/hwmon/lm95241.c b/drivers/hwmon/lm95241.c
> index 01c638e..ec02e30 100644
> --- a/drivers/hwmon/lm95241.c
> +++ b/drivers/hwmon/lm95241.c
> @@ -98,11 +98,16 @@ struct lm95241_data {
> };
>
> /* Conversions */
> -static int TempFromReg(u8 val_h, u8 val_l)
> +static int temp_from_reg_signed(u8 val_h, u8 val_l)
> {
> - if (val_h & 0x80)
> - return val_h - 0x100;
> - return val_h * 1000 + val_l * 1000 / 256;
> + s16 val_hl = (val_h << 8) | val_l;
> + return val_hl * 1000 / 256;
> +}
> +
> +static int temp_from_reg_unsigned(u8 val_h, u8 val_l)
> +{
> + u16 val_hl = (val_h << 8) | val_l;
> + return val_hl * 1000 / 256;
> }
>
> static struct lm95241_data *lm95241_update_device(struct device *dev)
> @@ -135,10 +140,13 @@ static ssize_t show_input(struct device *dev, struct device_attribute *attr,
> char *buf)
> {
> struct lm95241_data *data = lm95241_update_device(dev);
> + int index = to_sensor_dev_attr(attr)->index;
>
> return snprintf(buf, PAGE_SIZE - 1, "%d\n",
> - TempFromReg(data->temp[to_sensor_dev_attr(attr)->index],
> - data->temp[to_sensor_dev_attr(attr)->index + 1]));
> + !index || (data->config & index) ?
Hmm. This really should be:
+ !index || (data->config & (1 << (index / 2))) ?
It just _happens_ that (1 << (index / 2)) == index for index values 2
and 4, so your code works. But if we ever add support for a compatible
device with an extra temperature channel, it'll break. Not sure if the
rest of the driver code would properly cope with such a change anyway,
though.
Furthermore, I think that readability could be slightly improved by
changing "!index" to "index == 0", as this is neither an error
condition nor a boolean).
Readability could be improved even more with driver-wide changes but
this is obviously out-of-scope for this patch.
> + temp_from_reg_signed(data->temp[index], data->temp[index + 1]) :
> + temp_from_reg_unsigned(data->temp[index],
> + data->temp[index + 1]));
> }
>
> static ssize_t show_type(struct device *dev, struct device_attribute *attr,
--
Jean Delvare
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