Re: [PATCH v1 06/16] clk: starfive: Add JH7100 clock generator driver

[Andy Shevchenko <andy.shevchenko@xxxxxxxxx>]

On Tue, Oct 12, 2021 at 4:42 PM Emil Renner Berthing <kernel@xxxxxxxx> wrote:
>
> From: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
>
> Add a driver for the StarFive JH7100 clock generator.

...

> +config CLK_STARFIVE_JH7100
> +       bool "StarFive JH7100 clock support"
> +       depends on SOC_STARFIVE || COMPILE_TEST

> +       depends on OF

Why? I haven't found a compile dependency, so you reduce the test
scope (when COMPILE_TEST=y).

...

You are using
bits.h
mod_devicetable.h
which are not here

> +#include <linux/clk.h>
> +#include <linux/clk-provider.h>
> +#include <linux/debugfs.h>
> +#include <linux/device.h>
> +#include <linux/init.h>
> +#include <linux/io.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/overflow.h>
> +#include <linux/platform_device.h>

...

> +       value |= readl_relaxed(reg) & ~mask;

value is not masked, is it okay?

Usual pattern for this kind of operations is

value = (current & ~mask) | (value & mask);

> +       writel_relaxed(value, reg);

...

> +       if (div > max)
> +               div = max;
> +
> +       return div;

return min(div, max); ?

...

> +       rate = parent / div;
> +       if (rate < req->min_rate && div > 1) {
> +               div -= 1;
> +               rate = parent / div;
> +       }

Seems like homegrown DIV_ROUND_UP() or so. Who will guarantee that
decreasing div by 1 will satisfy the conditional again?

...

> +#ifdef CONFIG_DEBUG_FS

Perhaps __maybe_unused?

> +#else
> +#define jh7100_clk_debug_init NULL
> +#endif

...

> +       if (idx >= JH7100_CLK_END) {

> +               dev_err(priv->dev, "%s: invalid index %u\n", __func__, idx);

__func__ means that the message has no value on its own. Make it
unique without using __func__, or drop completely.

> +               return ERR_PTR(-EINVAL);
> +       }

...

> +       for (idx = 0; idx < JH7100_CLK_PLL0_OUT; idx++) {
> +               struct clk_init_data init = {
> +                       .name = jh7100_clk_data[idx].name,
> +                       .ops = jh7100_clk_data[idx].ops,

> +                       .num_parents = ((jh7100_clk_data[idx].max & JH7100_CLK_MUX_MASK)
> +                                       >> JH7100_CLK_MUX_SHIFT) + 1,

With temporary variable this can be better written, or consider
something like this

                       .num_parents =
                               ((jh7100_clk_data[idx].max &
JH7100_CLK_MUX_MASK) >> JH7100_CLK_MUX_SHIFT) + 1,

> +                       .flags = jh7100_clk_data[idx].flags,
> +               };
> +               struct jh7100_clk *clk = &priv->reg[idx];

...

> +       while (idx > 0)
> +               clk_hw_unregister(&priv->reg[--idx].hw);

The

       while (idx--)
               clk_hw_unregister(&priv->reg[idx].hw);

is slightly better to read.

> +       return ret;
> +}

...

> +static int __init clk_starfive_jh7100_init(void)
> +{
> +       return platform_driver_probe(&clk_starfive_jh7100_driver,
> +                                    clk_starfive_jh7100_probe);
> +}

> +

No need to have this blank line.
> +subsys_initcall(clk_starfive_jh7100_init);

Any  explanation why subsys_initcall() is in use?

-- 
With Best Regards,
Andy Shevchenko