Subject: [PATCH v2 1/5] clk: samsung: add common clock framework support for Samsung platforms

From: [email-masked] (Mike Turquette)
Date: Tue, 30 Oct 2012 09:30:12 -0700

Hi Thomas,

Quoting Thomas Abraham (2012-10-07 10:10:51)
> +/* determine the output clock speed of the pll */
> +static unsigned long samsung_pll_clock_recalc_rate(struct clk_hw *hw,
> +                               unsigned long parent_rate)
> +{
> +       struct samsung_pll_clock *clk_pll = to_clk_pll(hw);
> +
> +       if (clk_pll->get_rate)
> +               return to_clk_pll(hw)->get_rate(parent_rate);

Why the extra indirection?  Does your samsung_pll_clock abstract several
different PLL implementations (with separate clock ops)?  If so, why not
make a unique struct for each PLL type?

> +
> +       return 0;
> +}
> +
> +/* round operation not supported */
> +static long samsung_pll_clock_round_rate(struct clk_hw *hw, unsigned long drate,
> +                               unsigned long *prate)
> +{
> +       return samsung_pll_clock_recalc_rate(hw, *prate);

Why is round_rate not supported?  How is returning the recalculated rate
the right thing here?

> +/*
> + * Allow platform specific implementations to attach set_rate and get_rate
> + * callbacks for the pll type clock. Typical calling sequence..
> + *
> + * struct clk *clk = clk_get(NULL, "pll-clk-name");
> + * samsung_pll_clk_set_cb(clk, pll_set_rate, pll_get_rate);
> + */
> +void __init samsung_pll_clk_set_cb(struct clk *clk,
> +                       int (*set_rate)(unsigned long rate),
> +                       unsigned long (*get_rate)(unsigned long rate))
> +{
> +       struct samsung_pll_clock *clk_pll;
> +       struct clk_hw *hw = __clk_get_hw(clk);
> +
> +       clk_pll = to_clk_pll(hw);
> +       clk_pll->set_rate = set_rate;
> +       clk_pll->get_rate = get_rate;
> +}

This answers my questions above having different PLL types.  Why not
just make seprate clk_hw structs for each PLL type instead of the extra
layer of abstraction + runtime assignment of clk ops?

Regards,
Mike