linux-kernel - Re: [PATCH v10 2/4] clk: clk-loongson2: add clock controller driver support

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Date:   Fri, 17 Feb 2023 14:15:42 -0800
From:   Stephen Boyd <sboyd@...nel.org>
To:     Huacai Chen <chenhuacai@...nel.org>,
        Jianmin Lv <lvjianmin@...ngson.cn>,
        Jiaxun Yang <jiaxun.yang@...goat.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Michael Turquette <mturquette@...libre.com>,
        Rob Herring <robh+dt@...nel.org>,
        WANG Xuerui <kernel@...0n.name>,
        Yang Li <yang.lee@...ux.alibaba.com>,
        devicetree@...r.kernel.org, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org, liupeibao@...ngson.cn,
        loongarch@...ts.linux.dev, wanghongliang@...ngson.cn,
        zhuyinbo@...ngson.cn
Subject: Re: [PATCH v10 2/4] clk: clk-loongson2: add clock controller driver support

Quoting zhuyinbo (2023-02-14 23:35:22)
> 
> 在 2023/2/11 上午7:42, Stephen Boyd 写道:
> > Quoting Yinbo Zhu (2022-11-28 19:41:55)
> >
> >> +
> >> +       mult = (val >> LOONGSON2_USB_FREQSCALE_SHIFT) &
> >> +                       clk_div_mask(LOONGSON2_USB_FREQSCALE_WIDTH);
> >> +
> >> +       rate = parent_rate * (mult + 1);
> >> +       do_div(rate, 8);
> > Why is do_div() being used?
> no expecial reason, I only want to get a result that rate divide 8.

Ok, you can use div_u64() here and simplify.

> >
> 
> you meaning is to use clk_parent_data to rework 
> loongson2_clk_pll_register  and drop
> 
> loongson2_obtain_fixed_clk_hw ?

Yes

> 
> >
> >> +}
> >> +
> >> +static void __init loongson2_clocks_init(struct device_node *np)
> >> +{
> >> +       struct clk_hw **hws;
> >> +       struct clk_hw_onecell_data *clk_hw_data;
> >> +       spinlock_t loongson2_clk_lock;
> >> +
> >> +       loongson2_pll_base = of_iomap(np, 0);
> >> +
> >> +       if (!loongson2_pll_base) {
> >> +               pr_err("clk: unable to map loongson2 clk registers\n");
> >> +               goto err;
> > return?
> sorry, I don't get it.  you meaning is that  remove "goto err". Instead, 
> add a "return".

Yes.

> >
> >> +       }
> >> +
> >> +       clk_hw_data = kzalloc(struct_size(clk_hw_data, hws, LOONGSON2_CLK_END),
> >> +                                       GFP_KERNEL);
> >> +       if (WARN_ON(!clk_hw_data))
> >> +               goto err;
[...]
> >> +
> >> +err:
> >> +       iounmap(loongson2_pll_base);
> >> +}
> >> +
> >> +CLK_OF_DECLARE(loongson2_clk, "loongson,ls2k-clk", loongson2_clocks_init);
> > Any reason this can't be a platform driver?
> 
> For the compatible consideration of other clock controllers of 
> Loongson-2 series in the future, the way of using dts can be
> 
> better compatible.
> 

Sorry that sentence doesn't make sense to me. The use of dts doesn't
require the use of CLK_OF_DECLARE.