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Message-ID: <772c8198-b793-345f-2b78-2733ba304559@samsung.com>
Date: Tue, 7 Jun 2022 13:52:03 +0900
From: Chanwoo Choi <cw00.choi@...sung.com>
To: AngeloGioacchino Del Regno
<angelogioacchino.delregno@...labora.com>,
Johnson Wang <johnson.wang@...iatek.com>, krzk+dt@...nel.org,
robh+dt@...nel.org, kyungmin.park@...sung.com
Cc: khilman@...nel.org, linux-pm@...r.kernel.org,
linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org,
linux-mediatek@...ts.infradead.org, jia-wei.chang@...iatek.com,
Project_Global_Chrome_Upstream_Group@...iatek.com
Subject: Re: [PATCH v6 2/2] PM / devfreq: mediatek: Introduce MediaTek CCI
devfreq driver
On 5/30/22 9:16 PM, AngeloGioacchino Del Regno wrote:
> Il 27/05/22 13:00, Johnson Wang ha scritto:
>> 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@...iatek.com>
>> Signed-off-by: Johnson Wang <johnson.wang@...iatek.com>
>> Acked-by: Chanwoo Choi <cw00.choi@...sung.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 | 441 ++++++++++++++++++++++++++++++
>> 3 files changed, 452 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..df42da35b312
>> --- /dev/null
>> +++ b/drivers/devfreq/mtk-cci-devfreq.c
>> @@ -0,0 +1,441 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * Copyright (C) 2022 MediaTek Inc.
>> + */
>> +
>
> ..snip..
>
>> +};
>> +
>> +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);
>> + return dev_err_probe(dev, ret,
>> + "failed to get intermediate clk: %d\n", ret);
>> + }
>> +
>> + drv->proc_reg = devm_regulator_get_optional(dev, "proc");
>
> In the devicetree binding for this driver, the "proc" regulator is *not* optional,
> but here you're using devm_regulator_get_optional.
>
> If this is not optional, you should use devm_regulator_get() instead.
>
>> + if (IS_ERR(drv->proc_reg)) {
>> + ret = PTR_ERR(drv->proc_reg);
>> + return dev_err_probe(dev, ret,
>> + "failed to get proc regulator: %d\n", ret);
>
> There's no need to print ret... dev_err_probe() takes care of that for you already:
> in this case, you're printing the value of ret twice.
>
I agree. better to remove the additional 'ret' printing
from dev_err_probe.
>> + }
>> +
>> + ret = regulator_enable(drv->proc_reg);
>
> If you move this call after the devm_regulator_get_optional() call for the sram
> vreg, you will be able to use dev_err_probe for the latter as well.
>
>> + if (ret) {
>> + dev_err(dev, "failed to enable proc regulator\n");
>
> Why aren't you using dev_err_probe here, like you've done for the other instances?
dev_err is enough because it means that get to regulator instance
via regulator_get_optional. If error from regulator_enable happen,
it depends on the internal logic of pmic driver.
>
>> + return ret;
>> + }
>> +
>> + drv->sram_reg = devm_regulator_get_optional(dev, "sram");
>> + if (IS_ERR(drv->sram_reg))
>> + drv->sram_reg = NULL;
>
> When you use regulator_get_optional() (including the devm_ variant of it), you
> shall return an error, if there's any... that's what the _optional() is for.
>
> if (IS_ERR(drv->sram_reg))
> return dev_err_probe(dev, PTR_ERR(drv->proc_reg),
> "failed to get sram regulator");
>
>> + else {
>> + ret = regulator_enable(drv->sram_reg);
>> + if (ret) {
>> + dev_err(dev, "failed to enable sram regulator\n");
>> + goto out_free_resources;
>> + }
>> + }
>> +
>
> Regards,
> Angelo
>
Hi Johnson,
Thanks for your work. Before merge, better to remove the
'ret' printing from dev_err_probe above. I'll merge it.
--
Best Regards,
Chanwoo Choi
Samsung Electronics
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