Hi Uwe, > From: Uwe Kleine-König, Sent: Monday, December 10, 2018 5:04 PM > > Hello, > > On Mon, Dec 10, 2018 at 05:09:31AM +0000, Yoshihiro Shimoda wrote: > > Thank you very much for your patches! > > I tested patches and both codes work correctly. > > \o/, that's actually better than I expected :-) > > > > > The value of div should be calculatable without a loop. Something like: > > > > > > > > divider = NSEC_PER_SEC * RCAR_PWM_MAX_CYCLE; > > > > tmp = (unsigned long long)period_ns * clk_rate + (divider - 1); > > > > do_div(tmp, divider); > > > > This should be do_div64_u64() because the divider is 1,023,000,000,000 (over 32-bits). > > Yes, I think Laurent did this part right. > > > > > div = ilog2(tmp - 1) + 1; > > > > > > > > You might want to check if my maths are right, I didn't test. > > > > > > I've noticed the same, and wrote the following patch last week, also untested. > > > I was planning to give it a try before sending it out, but as you've noticed > > > the same issue, here's the code if anyone wants to give it a try before I can. > > > Our calculations are similar, the main difference is the last line, and I > > > think yours read better. > > > > So, I'd like to apply Uwe's code to mainline. Uwe, may I send such a patch > > with your author and Singed-off-by? > > Please no, I cannot sing good enough for this :-) > > Honestly: If you take the authorship and write something like "Algorithm > suggested by Uwe Kleine-König and Laurent Pinchart" that's IMHO fine. Thank you for your reply. I got it. I'll make a patch with such comment :) Best regards, Yoshihiro Shimoda > Best regards > Uwe > > -- > Pengutronix e.K. | Uwe Kleine-König | > Industrial Linux Solutions | http://www.pengutronix.de/ |
