Re: [RFC v5 21/23] clockevents: initial support for mono to raw time conversion

[Nicolai Stange]

Nicolai Stange <nicsta...@gmail.com> writes:

> +static u32 __clockevents_calc_adjust_freq(u32 mult_ce_raw, u32 mult_cs_mono,
> +                                     u32 mult_cs_raw)
> +{
> +     u64 adj;
> +     int sign;
> +
> +     if (mult_cs_raw >= mult_cs_mono) {
> +             sign = 0;
> +             adj = mult_cs_raw - mult_cs_mono;
> +     } else {
> +             sign = 1;
> +             adj = mult_cs_mono - mult_cs_raw;
> +     }
> +
> +     adj *= mult_ce_raw;
> +     adj += mult_cs_mono / 2;
> +     do_div(adj, mult_cs_mono);
> +
> +     if (!sign) {
> +             /*
> +              * Never increase mult by more than 12.5%,
> +              * c.f. __clockevents_update_bounds().
> +              */
> +             adj = max_t(u64, adj, mult_ce_raw / 8);

This is wrong and should read as min_t(...), of course -- it's an upper
bound.


> +             if (U32_MAX - mult_ce_raw < adj)
> +                     return U32_MAX;
> +             return mult_ce_raw + (u32)adj;
> +     }
> +     if (adj >= mult_ce_raw)
> +             return 1;
> +     return mult_ce_raw - (u32)adj;
> +}