On Wed, May 27, 2015 at 07:08:38PM -0300, Paulo Zanoni wrote: > 2015-05-27 18:39 GMT-03:00 Paulo Zanoni <przanoni@xxxxxxxxx>: > > 2015-05-07 14:38 GMT-03:00 Damien Lespiau <damien.lespiau@xxxxxxxxx>: > >> Currently, if an odd divider improves the deviation (minimizes it), we > >> take that divider. The recommendation is to prefer even dividers. > > > > The doc says "It is preferred to get as close to the DCO central > > frequency as possible, but using an even divider value takes > > precedence.", but I'm wondering if they meant "prefer even over odd in > > case they have the same deviation" or just "even divider is preferred > > as long as it's on the deviation threshold, even if there's an odd > > divider with minimal/no deviation". I see you implement the last > > option - if you don't count the possible bug mentioned on my review of > > patch 12. > > > > Assuming the loop order will be fixed on patch 12, and assuming you > > are correctly interpreting the spec, then your patch does what it > > says, so: Reviewed-by: Paulo Zanoni <paulo.r.zanoni@xxxxxxxxx>. > > I kept looking at the spec, and the section that describes the 4 steps > for the algorithm totally clarifies what's the correct interpretation. > Please see step 4. An "even" divider with any acceptable deviation is > preferred over any possible "odd" divider, it doesn't matter what is > the best deviation of the "odd" dividers. Right, too bad I read that last, but that's indeed what I think and well and answered a previous comment with that already. > Considering this, I think we really should invert the loops as I > suggested on patch 12, and then we should modify this patch so that it > breaks the loop only after we've also iterated over all DCOs. I guess > these changes are a requirement for the R-B tags on patches 12 and 13 > as long as you don't have counter arguments. Yup, agreed. > We should still consider breaking the loop earlier in case we reach 0 > deviation, and we should still consider comparing the pdeviation with > the ndeviation before picking central_freq, dco_freq and divider. > These things are not requirements for the R-B tags, but, as I said, > i'd like to see your opinion. With v2, the break on deviation 0 would just be a "fast path" because we can't improve on that. Still worth doing as a follow up (I like having real diffs rather than v2/v3 with all the changes squashed). -- Damien _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
