linux-kernel - Re: [PATCH v1 2/3] clk: starfive: Add StarFive JH7110 PLL clock driver

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Date:   Fri, 24 Feb 2023 15:45:06 +0800
From:   Xingyu Wu <xingyu.wu@...rfivetech.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
CC:     <linux-riscv@...ts.infradead.org>, <devicetree@...r.kernel.org>,
        "Michael Turquette" <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Emil Renner Berthing <kernel@...il.dk>,
        Rob Herring <robh+dt@...nel.org>,
        Conor Dooley <conor@...nel.org>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Hal Feng <hal.feng@...rfivetech.com>,
        <linux-kernel@...r.kernel.org>, <linux-clk@...r.kernel.org>
Subject: Re: [PATCH v1 2/3] clk: starfive: Add StarFive JH7110 PLL clock
 driver

On 2023/2/23 18:10, Krzysztof Kozlowski wrote:
> On 23/02/2023 11:03, Xingyu Wu wrote:
>> On 2023/2/23 17:35, Krzysztof Kozlowski wrote:
>>> On 23/02/2023 10:32, Xingyu Wu wrote:
>>>> On 2023/2/23 16:56, Krzysztof Kozlowski wrote:
>>>>> On 21/02/2023 15:11, Xingyu Wu wrote:
>>>>>> Add driver for the StarFive JH7110 PLL clock controller and
>>>>>> modify the JH7110 system clock driver to rely on this PLL clocks.
>>>>>>
>>>>>> Signed-off-by: Xingyu Wu <xingyu.wu@...rfivetech.com>
>>>>>> ---
>>>>>
>>>>>
>>>>>> +
>>>>>> +static int jh7110_pll_clk_probe(struct platform_device *pdev)
>>>>>> +{
>>>>>> +	int ret;
>>>>>> +	struct of_phandle_args args;
>>>>>> +	struct regmap *pll_syscon_regmap;
>>>>>> +	unsigned int idx;
>>>>>> +	struct jh7110_clk_pll_priv *priv;
>>>>>> +	struct jh7110_clk_pll_data *data;
>>>>>> +	char *pll_name[JH7110_PLLCLK_END] = {
>>>>>> +		"pll0_out",
>>>>>> +		"pll1_out",
>>>>>> +		"pll2_out"
>>>>>> +	};
>>>>>> +
>>>>>> +	priv = devm_kzalloc(&pdev->dev,
>>>>>> +			    struct_size(priv, data, JH7110_PLLCLK_END),
>>>>>> +			    GFP_KERNEL);
>>>>>> +	if (!priv)
>>>>>> +		return -ENOMEM;
>>>>>> +
>>>>>> +	priv->dev = &pdev->dev;
>>>>>> +	ret = of_parse_phandle_with_fixed_args(pdev->dev.of_node, "starfive,sysreg", 0, 0, &args);
>>>>>
>>>>> 1. Wrong wrapping. Wrap code at 80 as coding style asks.
>>>>>
>>>>> 2. Why you are using syscon for normal, device MMIO operation? Your DTS
>>>>> also points that this is incorrect, hacky representation of hardware.
>>>>> Don't add devices to DT to fake places and then overuse syscon to fix
>>>>> that fake placement. The clock is in system registers, thus it must be
>>>>> there.
>>>>>
>>>>> 3. Even if this stays, why so complicated code instead of
>>>>> syscon_regmap_lookup_by_phandle()?
>>>>>
>>>>
>>>> Thanks for your advice. Will use syscon_regmap_lookup_by_phandle instead it
>>>> and remove useless part.
>>>
>>> So you ignored entirely part 2? This was the main comment... I am going
>>> to keep NAK-ing it then.
>> 
>> What I understand to mean is that I cannot use a fake node to operate syscon
>> registers. So I should move the PLL node under syscon node directly. Is it ok?
> 
> Yes, because it looks like entire PLL clock control is from the syscon
> node, thus the clocks are there.

Thanks for the guidance, I will modify it in the next patch.

Best regards,
Xingyu Wu