Re: [PATCH] clk: ingenic: jz4760: Update M/N/OD calculation algorithm

[Stephen Boyd]

Quoting Paul Cercueil (2022-12-14 04:37:04)
> The previous algorithm was pretty broken.
> 
> - The inner loop had a '(m > m_max)' condition, and the value of 'm'
>   would increase in each iteration;
> 
> - Each iteration would actually multiply 'm' by two, so it is not needed
>   to re-compute the whole equation at each iteration;
> 
> - It would loop until (m & 1) == 0, which means it would loop at most
>   once.
> 
> - The outer loop would divide the 'n' value by two at the end of each
>   iteration. This meant that for a 12 MHz parent clock and a 1.2 GHz
>   requested clock, it would first try n=12, then n=6, then n=3, then
>   n=1, none of which would work; the only valid value is n=2 in this
>   case.
> 
> Simplify this algorithm with a single for loop, which decrements 'n'
> after each iteration, addressing all of the above problems.
> 
> Fixes: bdbfc029374f ("clk: ingenic: Add support for the JZ4760")
> Cc: <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
> ---

Applied to clk-fixes