Re: [PATCH v2 2/2] phy: rockchip: Add Samsung HDMI/eDP Combo PHY driver

[Luis de Arquer]

Hi Cristian,

On Mon, 2024-02-05 at 13:24 +0200, Cristian Ciocaltea wrote:
> +
> +static bool hdptx_phy_clk_pll_calc(unsigned int data_rate,
> +				   struct ropll_config *cfg)
> +{
> +	const unsigned int fout = data_rate / 2, fref = 24000;
> +	unsigned long k = 0, lc, k_sub, lc_sub;
> +	unsigned int fvco, sdc;
> +	u32 mdiv, sdiv, n = 8;
> +
> +	for (sdiv = 16; sdiv >= 1; sdiv--) {
> +		if (sdiv % 2 && sdiv != 1)
> +			continue;
> +
> +		fvco = fout * sdiv;
> +
> +		if (fvco < 2000000 || fvco > 4000000)
> +			continue;
> +

What about adding a check to data_rate, maybe like

if (fout > 0x0FFFFFFF)
	return false;

or similar, before the for loop, to keep the multiplication safe?

Right now it would be redundant, given that data_rate was, at some
point, encoded in 28 bits within bus_width. But can prevent future pain,
especially after changing to phy_configure_opts_hdmi.

Luis