Re: [PATCH v7 4/9] clk: mediatek: Add MT2701 clock support

[James Liao <jamesjj.liao@mediatek.com>]

Hi Stephen,

On Fri, 2016-05-06 at 16:11 -0700, Stephen Boyd wrote:
> On 04/14, James Liao wrote:
> > diff --git a/drivers/clk/mediatek/clk-mt2701.c b/drivers/clk/mediatek/clk-mt2701.c
> > new file mode 100644
> > index 0000000..b4db141
> > --- /dev/null
> > +++ b/drivers/clk/mediatek/clk-mt2701.c
> > +static void __init mtk_infrasys_init(struct device_node *node)
> > +{
> > +	struct clk_onecell_data *clk_data;
> > +	int r;
> > +
> > +	clk_data = mtk_alloc_clk_data(CLK_INFRA_NR);
> > +
> > +	mtk_clk_register_gates(node, infra_clks, ARRAY_SIZE(infra_clks),
> > +						clk_data);
> > +	mtk_clk_register_factors(infra_fixed_divs, ARRAY_SIZE(infra_fixed_divs),
> > +						clk_data);
> > +
> > +	r = of_clk_add_provider(node, of_clk_src_onecell_get, clk_data);
> > +	if (r)
> > +		pr_err("%s(): could not register clock provider: %d\n",
> > +			__func__, r);
> > +}
> > +CLK_OF_DECLARE(mtk_infrasys, "mediatek,mt2701-infracfg", mtk_infrasys_init);
> 
> I'm still lost on the usage of CLK_OF_DECLARE here. What part of
> these clk controllers needs to be registered to make the timer
> work?

GPT (mtk-timer.c) may need infracfg and topckgen clocks. MT8173 for
example:

	timer: timer@10008000 {
	[...]
		clocks = <&infracfg CLK_INFRA_CLK_13M>,
			 <&topckgen CLK_TOP_RTC_SEL>;
	};

> > +	GATE_DISP1(CLK_MM_DPI_DIGL, "mm_dpi_digl", "dpi0_sel", 2),
> > +	GATE_DISP1(CLK_MM_DPI_ENGINE, "mm_dpi_eng", "mm_sel", 3),
> > +	GATE_DISP1(CLK_MM_DPI1_DIGL, "mm_dpi1_digl", "dpi1_sel", 4),
> > +	GATE_DISP1(CLK_MM_DPI1_ENGINE, "mm_dpi1_eng", "mm_sel", 5),
> > +	GATE_DISP1(CLK_MM_TVE_OUTPUT, "mm_tve_output", "tve_sel", 6),
> > +	GATE_DISP1(CLK_MM_TVE_INPUT, "mm_tve_input", "dpi0_sel", 7),
> > +	GATE_DISP1(CLK_MM_HDMI_PIXEL, "mm_hdmi_pixel", "dpi1_sel", 8),
> > +	GATE_DISP1(CLK_MM_HDMI_PLL, "mm_hdmi_pll", "hdmi_sel", 9),
> > +	GATE_DISP1(CLK_MM_HDMI_AUDIO, "mm_hdmi_audio", "apll_sel", 10),
> > +	GATE_DISP1(CLK_MM_HDMI_SPDIF, "mm_hdmi_spdif", "apll_sel", 11),
> > +	GATE_DISP1(CLK_MM_TVE_FMM, "mm_tve_fmm", "mm_sel", 14),
> > +};
> 
> I also don't understand why we don't have different files and
> drivers for all these different clock controllers? They all have
> a similar probe structure, sure, but otherwise these are
> different devices with different clks for them. The whole #ifdef
> thing in the later patch would go away too.

Yes, you are right. So you prefer to support subsystem clocks in
separated files such as clk-mt2701-mm.c, clk-mt2701-bdp.c and so on,
right?

But even if we implement subsystem clock in separated files, we still
need a way to make them optional. So the config options and #ifdef may
not be removed.

> > +	GATE_BDP1(CLK_BDP_BRG_RT_B, "brg_rt_bclk", "mm_sel", 12),
> > +	GATE_BDP1(CLK_BDP_BRG_RT_DRAM, "brg_rt_dram", "mm_sel", 13),
> > +	GATE_BDP1(CLK_BDP_LARBRT_DRAM, "larbrt_dram", "mm_sel", 14),
> > +	GATE_BDP1(CLK_BDP_TMDS_SYN, "tmds_syn", "hdmi_0_pll340m", 15),
> > +	GATE_BDP1(CLK_BDP_HDMI_MON, "hdmi_mon", "hdmi_0_pll340m", 16),
> > +};
> > +
> > +static void __init mtk_bdpsys_init(struct device_node *node)
> 
> Shouldn't be __init because it's driver probe path.

I use builtin_platform_driver_probe(clk_drv, clk_probe) to register this
driver, and it looks can be __init.

> > +{
> > +	struct clk_onecell_data *clk_data;
> > +	int r;
> > +
> > +	clk_data = mtk_alloc_clk_data(CLK_BDP_NR);
> > +
> > +	mtk_clk_register_gates(node, bdp_clks, ARRAY_SIZE(bdp_clks),
> > +						clk_data);
> > +
> > +	r = of_clk_add_provider(node, of_clk_src_onecell_get, clk_data);
> > +	if (r)
> > +		pr_err("%s(): could not register clock provider: %d\n",
> > +			__func__, r);
> > +}
> [...]
> > +
> > +static int __init clk_probe(struct platform_device *pdev)
> > +{
> > +	void (*clk_init)(struct device_node *);
> > +	const struct of_device_id *of_id;
> > +
> > +	of_id = of_match_node(of_clk_match_tbl, pdev->dev.of_node);
> > +	if (!of_id || !of_id->data)
> > +		return -EINVAL;
> > +
> > +	clk_init = of_id->data;
> > +	clk_init(pdev->dev.of_node);
> > +
> > +	return 0;
> > +}
> > +
> > +static struct platform_driver clk_drv = {
> 
> Please add some mtk here, 'clk_drv' is too generic.

OK. I'll add it in next patch.

> > +	.driver = {
> > +		.name = "mtk-clk",
> > +		.owner = THIS_MODULE,
> 
> This is unnecessary.

I'll remove it.

> > +		.of_match_table = of_match_ptr(of_clk_match_tbl),
> 
> Just drop of_match_ptr() because it's not helping. Also
> of_clk_match_tbl is too generic.

I'll change it.

> > +	},
> > +};
> > +
> > +builtin_platform_driver_probe(clk_drv, clk_probe);
> > +}
> > diff --git a/drivers/clk/mediatek/clk-mtk.h b/drivers/clk/mediatek/clk-mtk.h
> > index 32d2e45..8796acc 100644
> > --- a/drivers/clk/mediatek/clk-mtk.h
> > +++ b/drivers/clk/mediatek/clk-mtk.h
> > @@ -145,8 +146,35 @@ struct mtk_gate {
> [...]
> > +struct mtk_clk_divider {
> > +	int id;
> > +	const char *name;
> > +	const char *parent_name;
> > +	unsigned long flags;
> > +
> > +	uint32_t div_reg;
> 
> u32 is shorter

I'll change it.

> > +	unsigned char div_shift;
> > +	unsigned char div_width;
> > +	unsigned char clk_divider_flags;
> > +	const struct clk_div_table *clk_div_table;
> > +};