Re: [PATCH 1/3] clk: sunxi-ng: add mux and pll notifiers for A64 CPU clock

[Maxime Ripard]

On Thu, Sep 28, 2017 at 02:24:18PM +0000, icenowy@xxxxxxx wrote:
> å 2017-09-28 22:20ïMaxime Ripard åéï
> > On Thu, Sep 28, 2017 at 10:42:39AM +0000, icenowy@xxxxxxx wrote:
> > > > On Sat, Sep 23, 2017 at 12:15:29AM +0000, Icenowy Zheng wrote:
> > > > > The A64 PLL_CPU clock has the same instability if some factor changed
> > > > > without the PLL gated like other SoCs with sun6i-style CCU, e.g. A33,
> > > > > H3.
> > > > >
> > > > > Add the mux and pll notifiers for A64 CPU clock to workaround the
> > > > > problem.
> > > > >
> > > > > Fixes: c6a0637460c2 ("clk: sunxi-ng: Add A64 clocks")
> > > > > Signed-off-by: Icenowy Zheng <icenowy@xxxxxxx>
> > > > > ---
> > > > >  drivers/clk/sunxi-ng/ccu-sun50i-a64.c | 28
> > > > > +++++++++++++++++++++++++++-
> > > > >  1 file changed, 27 insertions(+), 1 deletion(-)
> > > > >
> > > > > diff --git a/drivers/clk/sunxi-ng/ccu-sun50i-a64.c
> > > > > b/drivers/clk/sunxi-ng/ccu-sun50i-a64.c
> > > > > index 2bb4cabf802f..b55fa69dd0c1 100644
> > > > > --- a/drivers/clk/sunxi-ng/ccu-sun50i-a64.c
> > > > > +++ b/drivers/clk/sunxi-ng/ccu-sun50i-a64.c
> > > > > @@ -879,11 +879,26 @@ static const struct sunxi_ccu_desc
> > > > > sun50i_a64_ccu_desc = {
> > > > >  	.num_resets	= ARRAY_SIZE(sun50i_a64_ccu_resets),
> > > > >  };
> > > > >
> > > > > +static struct ccu_pll_nb sun50i_a64_pll_cpu_nb = {
> > > > > +	.common	= &pll_cpux_clk.common,
> > > > > +	/* copy from pll_cpux_clk */
> > > > > +	.enable	= BIT(31),
> > > > > +	.lock	= BIT(28),
> > > > > +};
> > > > > +
> > > > > +static struct ccu_mux_nb sun50i_a64_cpu_nb = {
> > > > > +	.common		= &cpux_clk.common,
> > > > > +	.cm		= &cpux_clk.mux,
> > > > > +	.delay_us	= 1, /* > 8 clock cycles at 24 MHz */
> > > > > +	.bypass_index	= 1, /* index of 24 MHz oscillator */
> > > > > +};
> > > > > +
> > > > >
> > > > >  static int sun50i_a64_ccu_probe(struct platform_device *pdev)
> > > > >  {
> > > > >  	struct resource *res;
> > > > >  	void __iomem *reg;
> > > > >  	u32 val;
> > > > > +	int ret;
> > > > >
> > > > >  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > > > >  	reg = devm_ioremap_resource(&pdev->dev, res);
> > > > > @@ -897,7 +912,18 @@ static int sun50i_a64_ccu_probe(struct
> > > > > platform_device *pdev)
> > > > >
> > > > >  	writel(0x515, reg + SUN50I_A64_PLL_MIPI_REG);
> > > > >
> > > > > -	return sunxi_ccu_probe(pdev->dev.of_node, reg,
> > > > > &sun50i_a64_ccu_desc);
> > > > > +	ret = sunxi_ccu_probe(pdev->dev.of_node, reg, &sun50i_a64_ccu_desc);
> > > > > +	if (ret)
> > > > > +		return ret;
> > > > > +
> > > > > +	/* Gate then ungate PLL CPU after any rate changes */
> > > > > +	ccu_pll_notifier_register(&sun50i_a64_pll_cpu_nb);
> > > > > +
> > > > > +	/* Reparent CPU during PLL CPU rate changes */
> > > > > +	ccu_mux_notifier_register(pll_cpux_clk.common.hw.clk,
> > > > > +				  &sun50i_a64_cpu_nb);
> > > > > +
> > > > > +	return 0;
> > > >
> > > > So this is the fourth user of the exact same code, can you turn that
> > > > into a shared function?
> > > 
> > > I think it's not so worthful to extract the code, as:
> > 
> > It does, because the order is important. If you do not register the
> > notifiers in the right order, you have a bug, and:
> > 
> > > - the notifier structs contains info of the clocks
> > 
> > this should be passed as a parameter anyway,
> 
> So the function only does these two registers?

Yes.

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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