Re: [PATCH v3 2/2] PM / devfreq: mediatek: Introduce MediaTek CCI devfreq driver

[Chanwoo Choi <cwchoi00@gmail.com>]

On Wed, May 11, 2022 at 2:14 PM Johnson Wang <johnson.wang@mediatek.com> wrote:
>
> On Mon, 2022-05-09 at 20:51 +0900, Chanwoo Choi wrote:
> > On 22. 5. 9. 14:57, Johnson Wang wrote:
> > > On Sat, 2022-05-07 at 22:53 +0900, Chanwoo Choi wrote:
> > > > 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://urldefense.com/v3/__https://git.kernel.org/pub/scm/linux/kernel/git/chanwoo/linux.git/log/?h=devfreq-testing__;!!CTRNKA9wMg0ARbw!wnTkI_sh3TsliBPFP70DFwtSZGtKyPinFu9h2BwULWX-xrWF0C21rLV-n1HhstfmLw42$
> > > > > >
> > > > > > ---
> > > > > >    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_PASS
> > > > > > IVE,
> > > > > > +                                            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?
> > > >
> > >
> > > Hi Chanwoo,
> > >
> > > Thanks for your information.
> > > I've tested this patch based on the latest devfreq-testing branch.
> > > It encounters the same crash as Chen-Yu mentioned[1].
> > >
> > > [1]
> > > https://lore.kernel.org/linux-pm/YniX1w+oI1eOCmCx@google.com/T/#u
> >
> > Hi Johnson,
> >
> > Thanks for the test. I'll drop the last patch caused of crash.
> > And I'll send v3 patchset right now.
> >
> >
>
> Hi Chanwoo,
>
> With your v3 patchset, this CCI devfreq driver works properly on the
> target.
> Thanks!

Hi Johnson,

Thanks for the test.
I'll send v4 with a Tested-by tag and some typo fixup And then I'll merge them.
As I know, you will send the next version of mediatek cci driver.
After that, I'll merge your patches. Thanks.

-- 
Best Regards,
Chanwoo Choi