Re: [PATCH RESEND] pwm: th1520: Remove requirement for mul_u64_u64_div_u64_roundup

[Michal Wilczynski]

On 5/25/26 17:51, Maurice Hieronymus wrote:
> On Mon, 2026-05-25 at 16:36 +0200, Michal Wilczynski wrote:
>>
>> To move forward, we should fix this by implementing the proper
>> generic
>> 64-bit math helper in the Rust abstractions, rather than narrowing
>> the
>> types here. Are you open to looking into adding the Rust equivalent
>> for
>> mul_u64_u64_div_u64_roundup instead?
> 
> I would be definitely down, to help with that.
> 
> Before I start working on it, a couple of clarification questions.
> 
> Should I implement this as a thin FFI wrapper calling the C-Functions?
> Or do you prefer to have a re-implementation in Rust.
> 
> Since mul_u64_u64_div_u64_roundup is a macro: Is it okay if this will
> be a small Rust function or should it be a macro as well?
> 
> Thanks a lot,

Apologies, I have to correct my statement from before after discussing
with Uwe. The reason the macro was used in the mentioned driver is NOT
that PWM controllers have 64-bit registers - Uwe isn't aware of that
being a real pattern either, and I was inferring it from the code rather
than from hardware reality. The actual reason the macros get used isn't
unified across drivers and we should pin that down separately rather
than block your patch on it.

So please hold off on the Rust helper for now - your initial patch might
be the right direction.

> 
> Maurice
> 

Best regards,
-- 
Michal Wilczynski <m.wilczynski@xxxxxxxxxxx>