linux-kernel - Re: [PATCH linux-next v2 6/6] ASoC: rsnd: add avb clocks

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Message-ID: <87o9a22hjt.wl-kuninori.morimoto.gx@renesas.com>
Date:   Tue, 4 Dec 2018 01:52:40 +0000
From:   Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>
To:     "jiada_wang@...tor.com" <jiada_wang@...tor.com>
CC:     "broonie@...nel.org" <broonie@...nel.org>,
        "perex@...ex.cz" <perex@...ex.cz>,
        "tiwai@...e.com" <tiwai@...e.com>,
        "vladimir_zapolskiy@...tor.com" <vladimir_zapolskiy@...tor.com>,
        "alsa-devel@...a-project.org" <alsa-devel@...a-project.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH linux-next v2 6/6] ASoC: rsnd: add avb clocks


Hi Jiada

> There are AVB Counter Clocks in ADG, each clock has 12bits integral
> and 8 bits fractional dividers which operates with S0D1ϕ clock.
> 
> This patch registers 8 AVB Counter Clocks when clock-cells of
> rcar_sound node is 2,
> 
> Signed-off-by: Jiada Wang <jiada_wang@...tor.com>
> ---
(snip)
> +struct clk_avb {
> +	struct clk_hw hw;
> +	unsigned int idx;
> +	struct rsnd_mod *mod;
> +	/* lock reg access */
> +	spinlock_t *lock;
> +};
> +
> +#define to_clk_avb(_hw) container_of(_hw, struct clk_avb, hw)

I like "hw_to_avb()"

> +static struct clk *rsnd_adg_clk_src_twocell_get(struct of_phandle_args *clkspec,
> +						void *data)
> +{
> +	unsigned int clkidx = clkspec->args[1];
> +	struct rsnd_adg *adg = data;
> +	const char *type;
> +	struct clk *clk;
> +
> +	switch (clkspec->args[0]) {
> +	case ADG_FIX:
> +		type = "fixed";
> +		if (clkidx >= CLKOUTMAX) {
> +			pr_err("Invalid %s clock index %u\n", type,
> +			       clkidx);
> +			return ERR_PTR(-EINVAL);
> +		}
> +		clk = adg->clkout[clkidx];
> +		break;
> +	case ADG_AVB:
> +		type = "avb";
> +		if (clkidx >= AVB_CLK_NUM) {
> +			pr_err("Invalid %s clock index %u\n", type,
> +			       clkidx);
> +			return ERR_PTR(-EINVAL);
> +		}
> +		clk = adg->clkavb[clkidx];
> +		break;
> +	default:
> +		pr_err("Invalid ADG clock type %u\n", clkspec->args[0]);
> +		return ERR_PTR(-EINVAL);
> +	}
> +
> +	return clk;
> +}

In this function
1) I don't think you need to use "char *type".
2) If you use "clkidx = clkspec->args[1]", having same name for "clkspec->args[0]"
   is readable.
3) please use dev_err() instad of pr_err()
   I think data can be priv, and you can use rsnd_priv_to_adg(), rsnd_priv_to_dev()

> +static void clk_avb_div_write(struct rsnd_mod *mod, u32 data, int idx)
(snip)
> +static u32 clk_avb_div_read(struct rsnd_mod *mod, int idx)

To reduce confusion, and be more redable code,
I think these function can be

	clk_avb_div_write(struct rsnd_adg *adg, u32 data);
	clk_avb_div_read(struct rsnd_adg *adg);

> +static int clk_avb_set_rate(struct clk_hw *hw, unsigned long rate,
> +			    unsigned long parent_rate)
> +{
> +	struct clk_avb *avb = to_clk_avb(hw);
> +	unsigned int div = clk_avb_calc_div(rate, parent_rate);
> +	u32 val;
> +
> +	val = clk_avb_div_read(avb->mod, avb->idx) & ~AVB_DIV_MASK;
> +	clk_avb_div_write(avb->mod, val | div, avb->idx);
> +
> +	return 0;
> +}

Why do we need to care about ~AVB_DIV_MASK area ?
These are 0 Reserved, I think.

> +static const struct clk_ops clk_avb_ops = {
> +	.enable = clk_avb_enable,
> +	.disable = clk_avb_disable,
> +	.is_enabled = clk_avb_is_enabled,
> +	.recalc_rate = clk_avb_recalc_rate,
> +	.round_rate = clk_avb_round_rate,
> +	.set_rate = clk_avb_set_rate,
> +};

This is not a big deal, but I like tab aligned ops

> +static struct clk *clk_register_avb(struct device *dev, struct rsnd_mod *mod,
> +				    unsigned int id, spinlock_t *lock)
> +{
> +	struct clk_init_data init;
> +	struct clk_avb *avb;
> +	struct clk *clk;
> +	char name[AVB_CLK_NAME_SIZE];
> +	const char *parent_name = ADG_CLK_NAME;
> +
> +	avb = devm_kzalloc(dev, sizeof(*avb), GFP_KERNEL);
> +	if (!avb)
> +		return ERR_PTR(-ENOMEM);
> +
> +	snprintf(name, AVB_CLK_NAME_SIZE, "%s%u", AVB_CLK_NAME, id);
> +
> +	avb->idx = id;
> +	avb->lock = lock;
> +	avb->mod = mod;
> +
> +	/* Register the clock. */
> +	init.name = name;
> +	init.ops = &clk_avb_ops;
> +	init.flags = CLK_IS_BASIC;
> +	init.parent_names = &parent_name;
> +	init.num_parents = 1;
> +
> +	avb->hw.init = &init;
> +
> +	/* init DIV to a valid state */
> +	clk_avb_div_write(avb->mod, avb->idx, AVB_MAX_DIV);

Please check parameter, I think you want to do is

	- clk_avb_div_write(avb->mod, avb->idx, AVB_MAX_DIV);
	+ clk_avb_div_write(avb->mod, AVB_MAX_DIV, avb->idx);

Best regards
---
Kuninori Morimoto