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Message-ID: <7eec74e32bb482ba6984c6789f598ee9965f49b3.camel@mediatek.com>
Subject: Re: [RESEND v4 2/2] PM / devfreq: mediatek: Introduce MediaTek CCI
 devfreq driver
From:   Johnson Wang <johnson.wang@mediatek.com>
To:     Chen-Yu Tsai <wenst@chromium.org>
CC:     <cw00.choi@samsung.com>, <krzk+dt@kernel.org>,
        <robh+dt@kernel.org>, <kyungmin.park@samsung.com>,
        <djakov@kernel.org>, <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>
Date:   Wed, 18 May 2022 20:19:20 +0800
In-Reply-To: <CAGXv+5Em2eq8g8phC7MVcEP-sCsSsKa9FQjOra2UN3pib_psLA@mail.gmail.com>
References: <20220513032832.17645-1-johnson.wang@mediatek.com>
         <20220513032832.17645-3-johnson.wang@mediatek.com>
         <CAGXv+5Em2eq8g8phC7MVcEP-sCsSsKa9FQjOra2UN3pib_psLA@mail.gmail.com>
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Hi Chen-Yu,

On Fri, 2022-05-13 at 11:54 +0800, Chen-Yu Tsai wrote:
> On Fri, May 13, 2022 at 11:31 AM Johnson Wang <
> johnson.wang@mediatek.com> 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: Jia-Wei Chang <jia-wei.chang@mediatek.com>
> > Signed-off-by: Johnson Wang <johnson.wang@mediatek.com>
> > Acked-by: Chanwoo Choi <cw00.choi@samsung.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!zzOSoso9udvDV3h6kYlmizFtbn3ACA5aS2jCAjKyvtu4z0fobv1mD5uF9YbPSme8l_NnR05unTxkZfDdzohu8asWZQ$
> >  
> > ---
> >  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..aa8c37eb4a06
> > --- /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;
> 
> Could you explain why the previous voltage setting is cached like
> this?
> 
> The CCI is sharing the regulator supply with one of the CPU clusters,
> and cpufreq could also change the voltage, so it's better to always
> retrieve the current setting directly from the regulator core. And
> those values might be cached iun the core, so it's unlikely to incur
> a significant cost.

Thanks for your suggestion.
I will modify it as mtk_ccifreq_set_voltage() does.
In that way I will try to remove pre_voltage member because it's no
longer needed.
> > +
> > +       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");
> 
> devm_ for this as well?
> 
I will modify it in the next version.

> > +       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.
> 
> expected?
> 
Maybe "the maximum" will be more appropriate?

> > +        */
> > +       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);
> 
> You don't need to enable the intermediate clock here. You shouldn't
> need
> to at all, as the CCF core will do it when the CCI clock is
> reparented
> over to it.

I will remove it and all of clk_disable_unprepare(drv->inter_clk) in
this file.
> 
> > +       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: %ld\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);
> 
> You don't need to "put" the resources you got using devm_ variants.
> If you really want to, you need to use devm_(clk|regulator)_put.
> 

I think I will remove these lines in the next version.

> > +
> > +       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,
> 
> AFAICT there's no sram supply for MT8183, so set max to zero as well?
> And you can just drop the two lines instead of explicitly setting
> them to zero.
> 

Sure, I will drop these two line.

> > +};
> > +
> > +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,
> 
> A side note about this: the min/max voltage values should also be set
> on the regulator nodes in the device tree. The range then gets
> enforced
> by the regulator core.
> 

Thanks for your reminder.
We will notice this when we are sending dts patches.

BRs,
Johnson Wang

> 
> Regards
> ChenYu
> 
> > +};
> > +
> > +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");
> > --
> > 2.18.0
> > 
> > 
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> > Linux-mediatek@lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-mediatek