On Wed, Oct 11, 2017 at 10:29 AM, sakari.ailus@xxxxxxxxxxxxxxx
<sakari.ailus@xxxxxxxxxxxxxxx> wrote:
> On Wed, Oct 11, 2017 at 04:14:37AM +0000, Zhi, Yong wrote:
>> > > +static unsigned int ipu3_css_scaler_get_exp(unsigned int counter,
>> > > + unsigned int divider) {
>> > > + unsigned int i = 0;
>> > > +
>> > > + while (counter <= divider / 2) {
>> > > + divider /= 2;
>> > > + i++;
>> > > + }
>> > > +
>> > > + return i;
> return (!counter || divider < counter) ?
> 0 : fls(divider / counter) - 1;
Extra division is here (I dunno if counter is always power of 2 but it
doesn't matter for compiler).
Basically above calculates how much bits we need to shift divider to
get it less than counter.
I would consider to use something from log2.h.
Roughly like
if (!counter || divider < counter)
return 0;
return order_base_2(divider) - order_base_2(counter);
--
With Best Regards,
Andy Shevchenko
