On Mon, Oct 07, 2024 at 09:48:40AM +0100, Colin Ian King wrote:
> The calculation of fout is using int multiplication and assigning
> the result to a u64, this can potentially overflow if the int variable
> mdiv is too large. Fix this by making the 65536 a u64 value to ensure a
> u64 multiplication is being performed to avoid the overflow.
>
> Fixes: 53990cf9d5b4 ("clk: imx: pll14xx: consolidate rate calculation")
> Signed-off-by: Colin Ian King <colin.i.king@xxxxxxxxx>
mdiv is always clamped in then 0-1023 range by one of these:
mdiv = FIELD_GET(MDIV_MASK, pll_div_ctl0);
mdiv = clamp(mdiv, 64, 1023);
so it can't overflow and the Fixes tag is unnecessary.
I think the reason why "fout" is declared as a u64 is because we were worried
that on 32 bit systems the "fout *=" operation could overflow. That looks
reasonable to me.
regards,
dan carpenter
