On 09/21/2015 09:58 AM, Rajendra Nayak wrote:
> []..
>
>>> +static inline int code_to_degc(u32 adc_code, const struct tsens_sensor *s)
>>> +{
>>> + int degc, num, den;
>>> +
>>> + num = (adc_code * SLOPE_FACTOR) - s->offset;
>>> + den = s->slope;
>>> +
>>> + if (num > 0)
>>> + degc = num + (den / 2);
>>> + else if (num < 0)
>>> + degc = num - (den / 2);
>>> + else
>>> + degc = num;
>>> +
>>> + degc /= den;
>>> +
>>> + return degc;
>>> +}
>>> +
>>> +int get_temp_common(struct tsens_device *tmdev, int id, int *temp)
>>> +{
>>> + struct tsens_sensor *s = &tmdev->sensor[id];
>>> + u32 code;
>>> + unsigned int sensor_addr;
>>> + int last_temp = 0, ret;
>>> +
>>> + sensor_addr = S0_ST_ADDR + s->hw_id * SN_ADDR_OFFSET;
>>> + ret = regmap_read(tmdev->map, sensor_addr, &code);
>>> + if (ret)
>>> + return ret;
>>> + last_temp = code & SN_ST_TEMP_MASK;
>>> +
>>> + *temp = code_to_degc(last_temp, s) * 1000;
>>> +
>>> + return 0;
>>> +}
>>
>> The way this function is coded the temperature will only ever change by
>> 1C (i.e., 1000mC). Is there a chance that you're losing precision in the
>> code_to_degc conversion that could be preserved perhaps?
>>
>> This is useful in scenarios where you use the power allocator governor
>> and the greater precision allows better power budget estimation.
>
> I'll take a look to see if we can get better precision. Thanks.
I checked, and it does not look like these devices can support better precision
than degC.
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