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

Andy Shevchenko
2021-10-12T15:41:03Z

On Tue, Oct 12, 2021 at 4:42 PM Emil Renner Berthing <kernel@esmil.dk> wrote:
>
> From: Geert Uytterhoeven <geert@linux-m68k.org>
>
> 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