linux-kernel - Re: [PATCH v5 2/2] clk: samsung: add initial exynos7870 clock driver

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Message-ID: <0a7c72cb-4b59-4146-8438-52d13b457a18@kernel.org>
Date: Wed, 5 Mar 2025 21:14:05 +0100
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Stephen Boyd <sboyd@...nel.org>, Alim Akhtar <alim.akhtar@...sung.com>,
 Chanwoo Choi <cw00.choi@...sung.com>, Conor Dooley <conor+dt@...nel.org>,
 Kaustabh Chakraborty <kauschluss@...root.org>,
 Michael Turquette <mturquette@...libre.com>, Rob Herring <robh@...nel.org>,
 Sylwester Nawrocki <s.nawrocki@...sung.com>
Cc: linux-samsung-soc@...r.kernel.org, linux-clk@...r.kernel.org,
 devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 2/2] clk: samsung: add initial exynos7870 clock driver

On 04/03/2025 19:16, Stephen Boyd wrote:
> Quoting Kaustabh Chakraborty (2025-02-28 19:57:13)
>> diff --git a/drivers/clk/samsung/clk-exynos7870.c b/drivers/clk/samsung/clk-exynos7870.c
>> new file mode 100644
>> index 0000000000000000000000000000000000000000..2ec4a4e489be30bd1cd2e6deac006bb8ac5bdc57
>> --- /dev/null
>> +++ b/drivers/clk/samsung/clk-exynos7870.c
>> @@ -0,0 +1,1830 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * Copyright (C) 2015 Samsung Electronics Co., Ltd.
>> + * Author: Kaustabh Chakraborty <kauschluss@...root.org>
>> + *
>> + * Common Clock Framework support for Exynos7870.
>> + */
>> +
>> +#include <linux/clk.h>
> 
> Please remove this include as this is a clk provider and not a clk
> consumer.


I fixed it up for all drivers.

> 
>> +#include <linux/clk-provider.h>
>> +#include <linux/of.h>
>> +#include <linux/of_device.h>
>> +#include <linux/platform_device.h>
>> +
>> +#include <dt-bindings/clock/samsung,exynos7870-cmu.h>
>> +
>> +#include "clk.h"
>> +#include "clk-exynos-arm64.h"
>> +
>> +/*
>> + * Register offsets for CMU_MIF (0x10460000)
>> + */
> [...]
>> +
>> +static const struct samsung_cmu_info peri_cmu_info __initconst = {
>> +       .gate_clks              = peri_gate_clks,
>> +       .nr_gate_clks           = ARRAY_SIZE(peri_gate_clks),
>> +       .clk_regs               = peri_clk_regs,
>> +       .nr_clk_regs            = ARRAY_SIZE(peri_clk_regs),
>> +       .nr_clk_ids             = PERI_NR_CLK,
>> +};
>> +
>> +static int __init exynos7870_cmu_probe(struct platform_device *pdev)
>> +{
>> +       const struct samsung_cmu_info *info;
>> +       struct device *dev = &pdev->dev;
>> +
>> +       info = of_device_get_match_data(dev);
> 
> Use device APIs please: device_get_match_data()


I expect here a follow up patch.

> 
>> +       exynos_arm64_register_cmu(dev, dev->of_node, info);
>> +
>> +       return 0;
>> +}
>> +
>> +static const struct of_device_id exynos7870_cmu_of_match[] = {
>> +       {
>> +               .compatible = "samsung,exynos7870-cmu-mif",
>> +               .data = &mif_cmu_info,
>> +       }, {
>> +               .compatible = "samsung,exynos7870-cmu-dispaud",
>> +               .data = &dispaud_cmu_info,
>> +       }, {
>> +               .compatible = "samsung,exynos7870-cmu-fsys",
>> +               .data = &fsys_cmu_info,
>> +       }, {
>> +               .compatible = "samsung,exynos7870-cmu-g3d",
>> +               .data = &g3d_cmu_info,
>> +       }, {
>> +               .compatible = "samsung,exynos7870-cmu-isp",
>> +               .data = &isp_cmu_info,
>> +       }, {
>> +               .compatible = "samsung,exynos7870-cmu-mfcmscl",
>> +               .data = &mfcmscl_cmu_info,
>> +       }, {
>> +               .compatible = "samsung,exynos7870-cmu-peri",
>> +               .data = &peri_cmu_info,
>> +       }, {
>> +       },
>> +};
>> +
>> +static struct platform_driver exynos7870_cmu_driver __refdata = {
> 
> Having __refdata here looks wrong.
> 
>> +       .driver = {
>> +               .name = "exynos7870-cmu",
>> +               .of_match_table = exynos7870_cmu_of_match,
>> +               .suppress_bind_attrs = true,
>> +       },
>> +       .probe = exynos7870_cmu_probe,
>> +};
>> +
>> +static int __init exynos7870_cmu_init(void)
>> +{
>> +       return platform_driver_register(&exynos7870_cmu_driver);
> 
> Is this supposed to be platform_driver_probe()? All the __init markings
> in the samsung clk driver look like potential problems if anything
> defers or is made into a module.

Indeed code is confusing but still correct. This is called from
core_initcall and nothing referencing __init/refdata can defer nor be a
module. There are modules but, AFAIR, they don't use __init/__refdata.

The __refdata here was probably so this can reference __initconst in
other places.

As you pointed out, probably the correct solution is to use
platform_driver_probe().


Best regards,
Krzysztof