[Nouveau] [PATCH v4 20/37] volt: add coefficients

[Ilia Mirkin]

On Tue, Apr 19, 2016 at 5:52 PM, Martin Peres <martin.peres at free.fr> wrote:
>> +                               result =  ((s64)info.arg[0] * 15625) >>
>> 18;
>> +                               result += ((s64)info.arg[1] * volt->speedo
>> * 15625) >> 18;
>> +                               result += ((s64)info.arg[2] * temp *
>> 15625) >> 10;
>> +                               result += ((s64)info.arg[3] * volt->speedo
>> * temp * 15625) >> 18;
>> +                               result += ((s64)info.arg[4] * volt->speedo
>> * volt->speedo * 15625) >> 30;
>> +                               result += ((s64)info.arg[5] * temp * temp
>> * 15625) >> 18;
>> +                               break;
>
>
> Well, I can only say that these values got us really really close to what
> nvidia does... On around 10 GPUs... So... until we know better, let's stick
> to them.
>
> Hopefully, we can figure out where this 15625 comes from. This patch is:

5^6. Really it's 10^6, but it's silly to multiply by 10^6 and then
divide by powers of 2. Instead that's factored out...

  -ilia