Re: [PATCH net-next v4 1/2] qed: Add infrastructure for PTP support.

[Richard Cochran]

On Sun, Feb 12, 2017 at 11:52:23AM +0000, Mintz, Yuval wrote:
> Just to clarify [since it's bit a meaningless otherwise] -
> this +8 is a HW-bug workaround.

Can you please explain exactly what the problem is?

Your code does

                period1 = div_s64(val * 1000000000, ppb);
                period1 -= 8;
                period1 >>= 4;

But correct rounding would be

                period1 = div_s64(val * 1000000000, ppb);
                period1 += 8;
                period1 >>= 4;

Thanks,
Richard