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

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Date:   Thu, 28 Sep 2017 18:42:39 +0800
From:   icenowy@...c.io
To:     Maxime Ripard <maxime.ripard@...e-electrons.com>
Cc:     devicetree@...r.kernel.org, linux-sunxi@...glegroups.com,
        linux-kernel@...r.kernel.org, Chen-Yu Tsai <wens@...e.org>,
        linux-clk@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 1/3] clk: sunxi-ng: add mux and pll notifiers for A64 CPU
 clock

在 2017-09-28 18:27，Maxime Ripard 写道：
> Hi,
> 
> 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@...c.io>
>> ---
>>  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:
- the notifier structs contains info of the clocks
- A31 seems not to need the PLL notifier.

> 
> Thanks!
> Maxime
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

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