Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:18 as permitted sender) client-ip=2620:137:e000::1:18;
Message-ID: <bc64a239-1f14-c55c-9868-55eb7fbd93c9@gmail.com>
Date:   Sat, 7 May 2022 22:53:24 +0900
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101
 Thunderbird/91.8.1
Subject: Re: [PATCH v3 2/2] PM / devfreq: mediatek: Introduce MediaTek CCI
 devfreq driver
Content-Language: en-US
To:     Johnson Wang <johnson.wang@mediatek.com>, cw00.choi@samsung.com,
        krzk+dt@kernel.org, robh+dt@kernel.org, kyungmin.park@samsung.com
Cc:     khilman@kernel.org, linux-pm@vger.kernel.org,
        linux-kernel@vger.kernel.org, devicetree@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org, jia-wei.chang@mediatek.com,
        Project_Global_Chrome_Upstream_Group@mediatek.com
References: <20220425125546.4129-1-johnson.wang@mediatek.com>
 <20220425125546.4129-3-johnson.wang@mediatek.com>
 <b533338d70830a7c58af8afec205c0db7c8a24f8.camel@mediatek.com>
From:   Chanwoo Choi <cwchoi00@gmail.com>
In-Reply-To: <b533338d70830a7c58af8afec205c0db7c8a24f8.camel@mediatek.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Precedence: bulk

On 22. 5. 6. 20:38, Johnson Wang wrote:
> On Mon, 2022-04-25 at 20:55 +0800, Johnson Wang wrote:
>> We introduce a devfreq driver for the MediaTek Cache Coherent
>> Interconnect
>> (CCI) used by some MediaTek SoCs.
>>
>> In this driver, we use the passive devfreq driver to get target
>> frequencies
>> and adjust voltages accordingly. In MT8183 and MT8186, the MediaTek
>> CCI
>> is supplied by the same regulators with the little core CPUs.
>>
>> Signed-off-by: Johnson Wang <johnson.wang@mediatek.com>
>> Signed-off-by: Jia-Wei Chang <jia-wei.chang@mediatek.com>
>> ---
>> This patch depends on "devfreq-testing"[1].
>> [1]
>> https://git.kernel.org/pub/scm/linux/kernel/git/chanwoo/linux.git/log/?h=devfreq-testing
>> ---
>>   drivers/devfreq/Kconfig           |  10 +
>>   drivers/devfreq/Makefile          |   1 +
>>   drivers/devfreq/mtk-cci-devfreq.c | 474
>> ++++++++++++++++++++++++++++++
>>   3 files changed, 485 insertions(+)
>>   create mode 100644 drivers/devfreq/mtk-cci-devfreq.c
>>
>> diff --git a/drivers/devfreq/Kconfig b/drivers/devfreq/Kconfig
>> index 87eb2b837e68..9754d8b31621 100644
>> --- a/drivers/devfreq/Kconfig
>> +++ b/drivers/devfreq/Kconfig
>> @@ -120,6 +120,16 @@ config ARM_TEGRA_DEVFREQ
>>   	  It reads ACTMON counters of memory controllers and adjusts
>> the
>>   	  operating frequencies and voltages with OPP support.
>>   
>> +config ARM_MEDIATEK_CCI_DEVFREQ
>> +	tristate "MEDIATEK CCI DEVFREQ Driver"
>> +	depends on ARM_MEDIATEK_CPUFREQ || COMPILE_TEST
>> +	select DEVFREQ_GOV_PASSIVE
>> +	help
>> +	  This adds a devfreq driver for MediaTek Cache Coherent
>> Interconnect
>> +	  which is shared the same regulators with the cpu cluster. It
>> can track
>> +	  buck voltages and update a proper CCI frequency. Use the
>> notification
>> +	  to get the regulator status.
>> +
>>   config ARM_RK3399_DMC_DEVFREQ
>>   	tristate "ARM RK3399 DMC DEVFREQ Driver"
>>   	depends on (ARCH_ROCKCHIP && HAVE_ARM_SMCCC) || \
>> diff --git a/drivers/devfreq/Makefile b/drivers/devfreq/Makefile
>> index 0b6be92a25d9..bf40d04928d0 100644
>> --- a/drivers/devfreq/Makefile
>> +++ b/drivers/devfreq/Makefile
>> @@ -11,6 +11,7 @@ obj-$(CONFIG_DEVFREQ_GOV_PASSIVE)	+=
>> governor_passive.o
>>   obj-$(CONFIG_ARM_EXYNOS_BUS_DEVFREQ)	+= exynos-bus.o
>>   obj-$(CONFIG_ARM_IMX_BUS_DEVFREQ)	+= imx-bus.o
>>   obj-$(CONFIG_ARM_IMX8M_DDRC_DEVFREQ)	+= imx8m-ddrc.o
>> +obj-$(CONFIG_ARM_MEDIATEK_CCI_DEVFREQ)	+= mtk-cci-devfreq.o
>>   obj-$(CONFIG_ARM_RK3399_DMC_DEVFREQ)	+= rk3399_dmc.o
>>   obj-$(CONFIG_ARM_SUN8I_A33_MBUS_DEVFREQ)	+= sun8i-a33-mbus.o
>>   obj-$(CONFIG_ARM_TEGRA_DEVFREQ)		+= tegra30-devfreq.o
>> diff --git a/drivers/devfreq/mtk-cci-devfreq.c b/drivers/devfreq/mtk-
>> cci-devfreq.c
>> new file mode 100644
>> index 000000000000..b3e31c45a57c
>> --- /dev/null
>> +++ b/drivers/devfreq/mtk-cci-devfreq.c
>> @@ -0,0 +1,474 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * Copyright (C) 2022 MediaTek Inc.
>> + */
>> +
>> +#include <linux/clk.h>
>> +#include <linux/devfreq.h>
>> +#include <linux/minmax.h>
>> +#include <linux/module.h>
>> +#include <linux/of.h>
>> +#include <linux/of_device.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/pm_opp.h>
>> +#include <linux/regulator/consumer.h>
>> +
>> +struct mtk_ccifreq_platform_data {
>> +	int min_volt_shift;
>> +	int max_volt_shift;
>> +	int proc_max_volt;
>> +	int sram_min_volt;
>> +	int sram_max_volt;
>> +};
>> +
>> +struct mtk_ccifreq_drv {
>> +	struct device *dev;
>> +	struct devfreq *devfreq;
>> +	struct regulator *proc_reg;
>> +	struct regulator *sram_reg;
>> +	struct clk *cci_clk;
>> +	struct clk *inter_clk;
>> +	int inter_voltage;
>> +	int pre_voltage;
>> +	unsigned long pre_freq;
>> +	/* Avoid race condition for regulators between notify and
>> policy */
>> +	struct mutex reg_lock;
>> +	struct notifier_block opp_nb;
>> +	const struct mtk_ccifreq_platform_data *soc_data;
>> +	int vtrack_max;
>> +};
>> +
>> +static int mtk_ccifreq_set_voltage(struct mtk_ccifreq_drv *drv, int
>> new_voltage)
>> +{
>> +	const struct mtk_ccifreq_platform_data *soc_data = drv-
>>> soc_data;
>> +	struct device *dev = drv->dev;
>> +	int pre_voltage, pre_vsram, new_vsram, vsram, voltage, ret;
>> +	int retry_max = drv->vtrack_max;
>> +
>> +	if (!drv->sram_reg) {
>> +		ret = regulator_set_voltage(drv->proc_reg, new_voltage,
>> +					    drv->soc_data-
>>> proc_max_volt);
>> +		goto out_set_voltage;
>> +	}
>> +
>> +	pre_voltage = regulator_get_voltage(drv->proc_reg);
>> +	if (pre_voltage < 0) {
>> +		dev_err(dev, "invalid vproc value: %d\n", pre_voltage);
>> +		return pre_voltage;
>> +	}
>> +
>> +	pre_vsram = regulator_get_voltage(drv->sram_reg);
>> +	if (pre_vsram < 0) {
>> +		dev_err(dev, "invalid vsram value: %d\n", pre_vsram);
>> +		return pre_vsram;
>> +	}
>> +
>> +	new_vsram = clamp(new_voltage + soc_data->min_volt_shift,
>> +			  soc_data->sram_min_volt, soc_data-
>>> sram_max_volt);
>> +
>> +	do {
>> +		if (pre_voltage <= new_voltage) {
>> +			vsram = clamp(pre_voltage + soc_data-
>>> max_volt_shift,
>> +				      soc_data->sram_min_volt,
>> new_vsram);
>> +			ret = regulator_set_voltage(drv->sram_reg,
>> vsram,
>> +						    soc_data-
>>> sram_max_volt);
>> +			if (ret)
>> +				return ret;
>> +
>> +			if (vsram == soc_data->sram_max_volt ||
>> +			    new_vsram == soc_data->sram_min_volt)
>> +				voltage = new_voltage;
>> +			else
>> +				voltage = vsram - soc_data-
>>> min_volt_shift;
>> +
>> +			ret = regulator_set_voltage(drv->proc_reg,
>> voltage,
>> +						    soc_data-
>>> proc_max_volt);
>> +			if (ret) {
>> +				regulator_set_voltage(drv->sram_reg,
>> pre_vsram,
>> +						      soc_data-
>>> sram_max_volt);
>> +				return ret;
>> +			}
>> +		} else if (pre_voltage > new_voltage) {
>> +			voltage = max(new_voltage,
>> +				      pre_vsram - soc_data-
>>> max_volt_shift);
>> +			ret = regulator_set_voltage(drv->proc_reg,
>> voltage,
>> +						    soc_data-
>>> proc_max_volt);
>> +			if (ret)
>> +				return ret;
>> +
>> +			if (voltage == new_voltage)
>> +				vsram = new_vsram;
>> +			else
>> +				vsram = max(new_vsram,
>> +					    voltage + soc_data-
>>> min_volt_shift);
>> +
>> +			ret = regulator_set_voltage(drv->sram_reg,
>> vsram,
>> +						    soc_data-
>>> sram_max_volt);
>> +			if (ret) {
>> +				regulator_set_voltage(drv->proc_reg,
>> pre_voltage,
>> +						      soc_data-
>>> proc_max_volt);
>> +				return ret;
>> +			}
>> +		}
>> +
>> +		pre_voltage = voltage;
>> +		pre_vsram = vsram;
>> +
>> +		if (--retry_max < 0) {
>> +			dev_err(dev,
>> +				"over loop count, failed to set
>> voltage\n");
>> +			return -EINVAL;
>> +		}
>> +	} while (voltage != new_voltage || vsram != new_vsram);
>> +
>> +out_set_voltage:
>> +	if (!ret)
>> +		drv->pre_voltage = new_voltage;
>> +
>> +	return ret;
>> +}
>> +
>> +static int mtk_ccifreq_target(struct device *dev, unsigned long
>> *freq,
>> +			      u32 flags)
>> +{
>> +	struct mtk_ccifreq_drv *drv = dev_get_drvdata(dev);
>> +	struct clk *cci_pll = clk_get_parent(drv->cci_clk);
>> +	struct dev_pm_opp *opp;
>> +	unsigned long opp_rate;
>> +	int voltage, pre_voltage, inter_voltage, target_voltage, ret;
>> +
>> +	if (!drv)
>> +		return -EINVAL;
>> +
>> +	if (drv->pre_freq == *freq)
>> +		return 0;
>> +
>> +	inter_voltage = drv->inter_voltage;
>> +
>> +	opp_rate = *freq;
>> +	opp = devfreq_recommended_opp(dev, &opp_rate, 1);
>> +	if (IS_ERR(opp)) {
>> +		dev_err(dev, "failed to find opp for freq: %ld\n",
>> opp_rate);
>> +		return PTR_ERR(opp);
>> +	}
>> +
>> +	mutex_lock(&drv->reg_lock);
>> +
>> +	voltage = dev_pm_opp_get_voltage(opp);
>> +	dev_pm_opp_put(opp);
>> +
>> +	if (unlikely(drv->pre_voltage <= 0))
>> +		pre_voltage = regulator_get_voltage(drv->proc_reg);
>> +	else
>> +		pre_voltage = drv->pre_voltage;
>> +
>> +	if (pre_voltage < 0) {
>> +		dev_err(dev, "invalid vproc value: %d\n", pre_voltage);
>> +		return pre_voltage;
>> +	}
>> +
>> +	/* scale up: set voltage first then freq. */
>> +	target_voltage = max(inter_voltage, voltage);
>> +	if (pre_voltage <= target_voltage) {
>> +		ret = mtk_ccifreq_set_voltage(drv, target_voltage);
>> +		if (ret) {
>> +			dev_err(dev, "failed to scale up voltage\n");
>> +			goto out_restore_voltage;
>> +		}
>> +	}
>> +
>> +	/* switch the cci clock to intermediate clock source. */
>> +	ret = clk_set_parent(drv->cci_clk, drv->inter_clk);
>> +	if (ret) {
>> +		dev_err(dev, "failed to re-parent cci clock\n");
>> +		goto out_restore_voltage;
>> +	}
>> +
>> +	/* set the original clock to target rate. */
>> +	ret = clk_set_rate(cci_pll, *freq);
>> +	if (ret) {
>> +		dev_err(dev, "failed to set cci pll rate: %d\n", ret);
>> +		clk_set_parent(drv->cci_clk, cci_pll);
>> +		goto out_restore_voltage;
>> +	}
>> +
>> +	/* switch the cci clock back to the original clock source. */
>> +	ret = clk_set_parent(drv->cci_clk, cci_pll);
>> +	if (ret) {
>> +		dev_err(dev, "failed to re-parent cci clock\n");
>> +		mtk_ccifreq_set_voltage(drv, inter_voltage);
>> +		goto out_unlock;
>> +	}
>> +
>> +	/*
>> +	 * If the new voltage is lower than the intermediate voltage or
>> the
>> +	 * original voltage, scale down to the new voltage.
>> +	 */
>> +	if (voltage < inter_voltage || voltage < pre_voltage) {
>> +		ret = mtk_ccifreq_set_voltage(drv, voltage);
>> +		if (ret) {
>> +			dev_err(dev, "failed to scale down voltage\n");
>> +			goto out_unlock;
>> +		}
>> +	}
>> +
>> +	drv->pre_freq = *freq;
>> +	mutex_unlock(&drv->reg_lock);
>> +
>> +	return 0;
>> +
>> +out_restore_voltage:
>> +	mtk_ccifreq_set_voltage(drv, pre_voltage);
>> +
>> +out_unlock:
>> +	mutex_unlock(&drv->reg_lock);
>> +	return ret;
>> +}
>> +
>> +static int mtk_ccifreq_opp_notifier(struct notifier_block *nb,
>> +				    unsigned long event, void *data)
>> +{
>> +	struct dev_pm_opp *opp = data;
>> +	struct mtk_ccifreq_drv *drv;
>> +	unsigned long freq, volt;
>> +
>> +	drv = container_of(nb, struct mtk_ccifreq_drv, opp_nb);
>> +
>> +	if (event == OPP_EVENT_ADJUST_VOLTAGE) {
>> +		freq = dev_pm_opp_get_freq(opp);
>> +
>> +		mutex_lock(&drv->reg_lock);
>> +		/* current opp item is changed */
>> +		if (freq == drv->pre_freq) {
>> +			volt = dev_pm_opp_get_voltage(opp);
>> +			mtk_ccifreq_set_voltage(drv, volt);
>> +		}
>> +		mutex_unlock(&drv->reg_lock);
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static struct devfreq_dev_profile mtk_ccifreq_profile = {
>> +	.target = mtk_ccifreq_target,
>> +};
>> +
>> +static int mtk_ccifreq_probe(struct platform_device *pdev)
>> +{
>> +	struct device *dev = &pdev->dev;
>> +	struct mtk_ccifreq_drv *drv;
>> +	struct devfreq_passive_data *passive_data;
>> +	struct dev_pm_opp *opp;
>> +	unsigned long rate, opp_volt;
>> +	int ret;
>> +
>> +	drv = devm_kzalloc(dev, sizeof(*drv), GFP_KERNEL);
>> +	if (!drv)
>> +		return -ENOMEM;
>> +
>> +	drv->dev = dev;
>> +	drv->soc_data = (const struct mtk_ccifreq_platform_data *)
>> +				of_device_get_match_data(&pdev->dev);
>> +	mutex_init(&drv->reg_lock);
>> +	platform_set_drvdata(pdev, drv);
>> +
>> +	drv->cci_clk = devm_clk_get(dev, "cci");
>> +	if (IS_ERR(drv->cci_clk)) {
>> +		ret = PTR_ERR(drv->cci_clk);
>> +		return dev_err_probe(dev, ret,
>> +				     "failed to get cci clk: %d\n",
>> ret);
>> +	}
>> +
>> +	drv->inter_clk = devm_clk_get(dev, "intermediate");
>> +	if (IS_ERR(drv->inter_clk)) {
>> +		ret = PTR_ERR(drv->inter_clk);
>> +		dev_err_probe(dev, ret,
>> +			      "failed to get intermediate clk: %d\n",
>> ret);
>> +		goto out_free_resources;
>> +	}
>> +
>> +	drv->proc_reg = devm_regulator_get_optional(dev, "proc");
>> +	if (IS_ERR(drv->proc_reg)) {
>> +		ret = PTR_ERR(drv->proc_reg);
>> +		dev_err_probe(dev, ret,
>> +			      "failed to get proc regulator: %d\n",
>> ret);
>> +		goto out_free_resources;
>> +	}
>> +
>> +	ret = regulator_enable(drv->proc_reg);
>> +	if (ret) {
>> +		dev_err(dev, "failed to enable proc regulator\n");
>> +		goto out_free_resources;
>> +	}
>> +
>> +	drv->sram_reg = regulator_get_optional(dev, "sram");
>> +	if (IS_ERR(drv->sram_reg))
>> +		drv->sram_reg = NULL;
>> +	else {
>> +		ret = regulator_enable(drv->sram_reg);
>> +		if (ret) {
>> +			dev_err(dev, "failed to enable sram
>> regulator\n");
>> +			goto out_free_resources;
>> +		}
>> +	}
>> +
>> +	/*
>> +	 * We assume min voltage is 0 and tracking target voltage using
>> +	 * min_volt_shift for each iteration.
>> +	 * The retry_max is 3 times of expeted iteration count.
>> +	 */
>> +	drv->vtrack_max = 3 * DIV_ROUND_UP(max(drv->soc_data-
>>> sram_max_volt,
>> +					       drv->soc_data-
>>> proc_max_volt),
>> +					   drv->soc_data-
>>> min_volt_shift);
>> +
>> +	ret = clk_prepare_enable(drv->cci_clk);
>> +	if (ret)
>> +		goto out_free_resources;
>> +
>> +	ret = clk_prepare_enable(drv->inter_clk);
>> +	if (ret)
>> +		goto out_disable_cci_clk;
>> +
>> +	ret = dev_pm_opp_of_add_table(dev);
>> +	if (ret) {
>> +		dev_err(dev, "failed to add opp table: %d\n", ret);
>> +		goto out_disable_inter_clk;
>> +	}
>> +
>> +	rate = clk_get_rate(drv->inter_clk);
>> +	opp = dev_pm_opp_find_freq_ceil(dev, &rate);
>> +	if (IS_ERR(opp)) {
>> +		ret = PTR_ERR(opp);
>> +		dev_err(dev, "failed to get intermediate opp: %d\n",
>> ret);
>> +		goto out_remove_opp_table;
>> +	}
>> +	drv->inter_voltage = dev_pm_opp_get_voltage(opp);
>> +	dev_pm_opp_put(opp);
>> +
>> +	rate = U32_MAX;
>> +	opp = dev_pm_opp_find_freq_floor(drv->dev, &rate);
>> +	if (IS_ERR(opp)) {
>> +		dev_err(dev, "failed to get opp\n");
>> +		ret = PTR_ERR(opp);
>> +		goto out_remove_opp_table;
>> +	}
>> +
>> +	opp_volt = dev_pm_opp_get_voltage(opp);
>> +	dev_pm_opp_put(opp);
>> +	ret = mtk_ccifreq_set_voltage(drv, opp_volt);
>> +	if (ret) {
>> +		dev_err(dev, "failed to scale to highest voltage %lu in
>> proc_reg\n",
>> +			opp_volt);
>> +		goto out_remove_opp_table;
>> +	}
>> +
>> +	passive_data = devm_kzalloc(dev, sizeof(struct
>> devfreq_passive_data),
>> +				    GFP_KERNEL);
>> +	if (!passive_data) {
>> +		ret = -ENOMEM;
>> +		goto out_remove_opp_table;
>> +	}
>> +
>> +	passive_data->parent_type = CPUFREQ_PARENT_DEV;
>> +	drv->devfreq = devm_devfreq_add_device(dev,
>> &mtk_ccifreq_profile,
>> +					       DEVFREQ_GOV_PASSIVE,
>> +					       passive_data);
>> +	if (IS_ERR(drv->devfreq)) {
>> +		ret = -EPROBE_DEFER;
>> +		dev_err(dev, "failed to add devfreq device: %d\n",
>> +			PTR_ERR(drv->devfreq));
>> +		goto out_remove_opp_table;
>> +	}
>> +
>> +	drv->opp_nb.notifier_call = mtk_ccifreq_opp_notifier;
>> +	ret = dev_pm_opp_register_notifier(dev, &drv->opp_nb);
>> +	if (ret) {
>> +		dev_err(dev, "failed to register opp notifier: %d\n",
>> ret);
>> +		goto out_remove_devfreq_device;
>> +	}
>> +	return 0;
>> +
>> +out_remove_devfreq_device:
>> +	devm_devfreq_remove_device(dev, drv->devfreq);
>> +
>> +out_remove_opp_table:
>> +	dev_pm_opp_of_remove_table(dev);
>> +
>> +out_disable_inter_clk:
>> +	clk_disable_unprepare(drv->inter_clk);
>> +
>> +out_disable_cci_clk:
>> +	clk_disable_unprepare(drv->cci_clk);
>> +
>> +out_free_resources:
>> +	if (regulator_is_enabled(drv->proc_reg))
>> +		regulator_disable(drv->proc_reg);
>> +	if (drv->sram_reg && regulator_is_enabled(drv->sram_reg))
>> +		regulator_disable(drv->sram_reg);
>> +
>> +	if (!IS_ERR(drv->proc_reg))
>> +		regulator_put(drv->proc_reg);
>> +	if (!IS_ERR(drv->sram_reg))
>> +		regulator_put(drv->sram_reg);
>> +	if (!IS_ERR(drv->cci_clk))
>> +		clk_put(drv->cci_clk);
>> +	if (!IS_ERR(drv->inter_clk))
>> +		clk_put(drv->inter_clk);
>> +
>> +	return ret;
>> +}
>> +
>> +static int mtk_ccifreq_remove(struct platform_device *pdev)
>> +{
>> +	struct device *dev = &pdev->dev;
>> +	struct mtk_ccifreq_drv *drv;
>> +
>> +	drv = platform_get_drvdata(pdev);
>> +
>> +	dev_pm_opp_unregister_notifier(dev, &drv->opp_nb);
>> +	dev_pm_opp_of_remove_table(dev);
>> +	clk_disable_unprepare(drv->inter_clk);
>> +	clk_disable_unprepare(drv->cci_clk);
>> +	regulator_disable(drv->proc_reg);
>> +	if (drv->sram_reg)
>> +		regulator_disable(drv->sram_reg);
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct mtk_ccifreq_platform_data mt8183_platform_data =
>> {
>> +	.min_volt_shift = 100000,
>> +	.max_volt_shift = 200000,
>> +	.proc_max_volt = 1150000,
>> +	.sram_min_volt = 0,
>> +	.sram_max_volt = 1150000,
>> +};
>> +
>> +static const struct mtk_ccifreq_platform_data mt8186_platform_data =
>> {
>> +	.min_volt_shift = 100000,
>> +	.max_volt_shift = 250000,
>> +	.proc_max_volt = 1118750,
>> +	.sram_min_volt = 850000,
>> +	.sram_max_volt = 1118750,
>> +};
>> +
>> +static const struct of_device_id mtk_ccifreq_machines[] = {
>> +	{ .compatible = "mediatek,mt8183-cci", .data =
>> &mt8183_platform_data },
>> +	{ .compatible = "mediatek,mt8186-cci", .data =
>> &mt8186_platform_data },
>> +	{ },
>> +};
>> +MODULE_DEVICE_TABLE(of, mtk_ccifreq_machines);
>> +
>> +static struct platform_driver mtk_ccifreq_platdrv = {
>> +	.probe	= mtk_ccifreq_probe,
>> +	.remove	= mtk_ccifreq_remove,
>> +	.driver = {
>> +		.name = "mtk-ccifreq",
>> +		.of_match_table = mtk_ccifreq_machines,
>> +	},
>> +};
>> +module_platform_driver(mtk_ccifreq_platdrv);
>> +
>> +MODULE_DESCRIPTION("MediaTek CCI devfreq driver");
>> +MODULE_AUTHOR("Jia-Wei Chang <jia-wei.chang@mediatek.com>");
>> +MODULE_LICENSE("GPL v2");
> 
> Hi Chanwoo,
> 
> Just a kindly ping.
> Could you please give me some suggestion on this patch?
> Thanks!
> 
> BRs,
> Johnson Wang
> 

Hi Johnson,

Sorry for late reply.But I replied it yesterday as following:
Maybe, this reply[1] has not yet arrrived at your mail box.
[1] 
https://lore.kernel.org/lkml/0846a062-2ea2-e6d4-03c8-992c2f2e24a0@gmail.com/T/#m3bc609d805d6e74ec7a105be0511926b4afbbaef

As I described on reply[1], I updated the patches on devfreq-testing
branch. Could you please test your patches based on devfreq-testing
branch?

-- 
Best Regards,
Samsung Electronics
Chanwoo Choi