[U-Boot] Illegal use of FP ops in clock_ti814x.c

Tom Rini
2014-02-21T19:14:51Z

On Mon, Oct 28, 2013 at 11:19:53PM +0000, M?ns Rullg?rd wrote:

> Wolfgang Denk <wd@denx.de> writes:
>
> > Dear Matt,
> >
> > I hope you are the right person to address this to - if not, please
> > help to redirect to the current responsible developer.
> >
> > Function pll_sigma_delta_val() in arch/arm/cpu/armv7/am33xx/clock_ti814x.c
> > incorrectly uses "float" data, which results in FP operations which
> > are not permitted in U-Boot.
> >
> > The actual computation appears simple enough so a rewrite of the code
> > without using any floating point operations should be fairly easy, but
> > I don't understand the actual logic of this code, so I'd rather leave
> > this to someone who does.
> >
> > Could you please help and clean up these three lines of code?
>
> Something like this should be equivalent. That said, it looks
> suspiciously like it's meant to simply do a division and round up. If
> that is the case, +225 should be +249. It probably makes no difference
> for the values actually encountered.
> Acked-by: Matt Porter <mporter@linaro.org>
>
>
> diff --git a/arch/arm/cpu/armv7/am33xx/clock_ti814x.c b/arch/arm/cpu/armv7/am33xx/clock_ti814x.c
> index ef14f47..9b5a47b 100644
> --- a/arch/arm/cpu/armv7/am33xx/clock_ti814x.c
> +++ b/arch/arm/cpu/armv7/am33xx/clock_ti814x.c
> @@ -211,11 +211,8 @@ static u32 pll_dco_freq_sel(u32 clkout_dco)
> static u32 pll_sigma_delta_val(u32 clkout_dco)
> {
> u32 sig_val = 0;
> - float frac_div;
>
> - frac_div = (float) clkout_dco / 250;
> - frac_div = frac_div + 0.90;
> - sig_val = (int)frac_div;
> + sig_val = (clkout_dco + 225) / 250;
> sig_val = sig_val << 24;
>
> return sig_val;

With a massively re-worded commit message, applied to u-boot-ti/master,
thanks!

--
Tom
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