On 5/7/19 6:55 AM, Guenter Roeck wrote:
> Hi Florian,
>
> On 5/6/19 3:41 PM, Florian Fainelli wrote:
>> If the SCMI firmware implementation is reporting values in a scale that
>> is different from the HWMON units, we need to scale up or down the value
>> according to how far appart they are.
>>
>> Signed-off-by: Florian Fainelli <f.fainelli@xxxxxxxxx>
>> ---
>> drivers/hwmon/scmi-hwmon.c | 55 +++++++++++++++++++++++++++++++-------
>> 1 file changed, 46 insertions(+), 9 deletions(-)
>>
>> diff --git a/drivers/hwmon/scmi-hwmon.c b/drivers/hwmon/scmi-hwmon.c
>> index a80183a488c5..e9913509cb88 100644
>> --- a/drivers/hwmon/scmi-hwmon.c
>> +++ b/drivers/hwmon/scmi-hwmon.c
>> @@ -18,6 +18,51 @@ struct scmi_sensors {
>> const struct scmi_sensor_info **info[hwmon_max];
>> };
>> +static enum hwmon_sensor_types scmi_types[] = {
>> + [TEMPERATURE_C] = hwmon_temp,
>> + [VOLTAGE] = hwmon_in,
>> + [CURRENT] = hwmon_curr,
>> + [POWER] = hwmon_power,
>> + [ENERGY] = hwmon_energy,
>> +};
>> +
>> +static u64 scmi_hwmon_scale(const struct scmi_sensor_info *sensor,
>> u64 value)
>> +{
>> + u64 scaled_value = value;
>
> I don't think that variable is necessary.
>
>> + s8 desired_scale;
>
> Just scale ? Also, you could assign scale here directly, and subtract
> the offset below. Then "n" would not be necessary.
> Such as
> s8 scale = sensor->scale; // assuming scale is s8
> ...
> case CURRENT:
> scale += 3;
> ...
>
> That would also be less confusing, since it would avoid the double
> negation.
>
>> + int n, p;
>
>> +
>> + switch (sensor->type) {
>> + case TEMPERATURE_C:
>> + case VOLTAGE:
>> + case CURRENT:
>> + /* fall through */
> Unnecessary comment
Is not removing the comment going to upset gcc when using
-Wimplicit-fallthrough?
>
>> + desired_scale = -3;
>> + break;
>> + case POWER:
>> + case ENERGY:
>> + /* fall through */
> Unnecessary comment.
>
>> + desired_scale = -6;
>> + break;
>> + default:
>> + return scaled_value;
>
> Here we presumably want a scale of 0. However, if the scale passed
> from SCMI is, say, -5 or +5, we return the original (unadjusted)
> value. Seems to me we would still want to adjust the value to match
> hwmon expectations. Am I missing something ?
You raise a valid point, not that could happen today because if the
sensor type has a value we don't recognize, we have not registered it,
so we would not even try to read rom it, but let's be future proof.
>
>> + }
>> +
>> + n = (s8)sensor->scale - desired_scale;
>> + if (n == 0)
>
> Indentation seems off here.
>
>> + return scaled_value;
>> +
>> + for (p = 0; p < abs(n); p++) {
>> + /* Need to scale up from sensor to HWMON */
>> + if (n > 0)
>> + scaled_value *= 10;
>> + else
>> + do_div(scaled_value, 10);
>> + }
>
> Something like
>
> factor = pow10(abs(scale));
> if (scale > 0)
> value *= factor;
> else
> do_div(value, factor);
>
> would avoid the repeated abs() and do_div(). Unfortunately there is
> no pow10() helper, so you would have to write that. Still, I think
> that would be much more efficient.
Sounds reasonable. Thanks for your feedback!
--
Florian
