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Subject: Re: [PATCH v10 11/19] PM / devfreq: tegra20: Deprecate in a favor
 of emc-stat based driver
To:     Dmitry Osipenko <digetx@gmail.com>,
        Thierry Reding <thierry.reding@gmail.com>,
        Jonathan Hunter <jonathanh@nvidia.com>,
        Georgi Djakov <georgi.djakov@linaro.org>,
        Rob Herring <robh+dt@kernel.org>,
        Michael Turquette <mturquette@baylibre.com>,
        Stephen Boyd <sboyd@kernel.org>,
        Peter De Schrijver <pdeschrijver@nvidia.com>,
        MyungJoo Ham <myungjoo.ham@samsung.com>,
        Kyungmin Park <kyungmin.park@samsung.com>,
        Mikko Perttunen <cyndis@kapsi.fi>,
        Viresh Kumar <vireshk@kernel.org>,
        Peter Geis <pgwipeout@gmail.com>,
        Nicolas Chauvet <kwizart@gmail.com>,
        Krzysztof Kozlowski <krzk@kernel.org>
Cc:     linux-tegra@vger.kernel.org, linux-pm@vger.kernel.org,
        linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org
From:   Chanwoo Choi <cw00.choi@samsung.com>
Organization: Samsung Electronics
Message-ID: <8b173eba-1587-19e3-296a-84f3c88ee96c@samsung.com>
Date:   Mon, 23 Nov 2020 16:02:26 +0900
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References: <20201123002723.28463-1-digetx@gmail.com>
        <CGME20201123003309epcas1p4b8eead07cefc84537160a2b867d61ee7@epcas1p4.samsung.com>
        <20201123002723.28463-12-digetx@gmail.com>
Precedence: bulk

On 11/23/20 9:27 AM, Dmitry Osipenko wrote:
> Remove tegra20-devfreq in order to replace it with a EMC_STAT based
> devfreq driver. Previously we were going to use MC_STAT based
> tegra20-devfreq driver because EMC_STAT wasn't working properly, but
> now that problem is resolved. This resolves complications imposed by
> the removed driver since it was depending on both EMC and MC drivers
> simultaneously.
> 
> Acked-by: Chanwoo Choi <cw00.choi@samsung.com>
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> ---
>  MAINTAINERS                       |   1 -
>  drivers/devfreq/Kconfig           |  10 --
>  drivers/devfreq/Makefile          |   1 -
>  drivers/devfreq/tegra20-devfreq.c | 210 ------------------------------
>  4 files changed, 222 deletions(-)
>  delete mode 100644 drivers/devfreq/tegra20-devfreq.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 5f10105cac6f..56c560320f00 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -11370,7 +11370,6 @@ L:	linux-pm@vger.kernel.org
>  L:	linux-tegra@vger.kernel.org
>  T:	git git://git.kernel.org/pub/scm/linux/kernel/git/chanwoo/linux.git
>  S:	Maintained
> -F:	drivers/devfreq/tegra20-devfreq.c
>  F:	drivers/devfreq/tegra30-devfreq.c
>  
>  MEMORY MANAGEMENT
> diff --git a/drivers/devfreq/Kconfig b/drivers/devfreq/Kconfig
> index 0ee36ae2fa79..00704efe6398 100644
> --- a/drivers/devfreq/Kconfig
> +++ b/drivers/devfreq/Kconfig
> @@ -121,16 +121,6 @@ config ARM_TEGRA_DEVFREQ
>  	  It reads ACTMON counters of memory controllers and adjusts the
>  	  operating frequencies and voltages with OPP support.
>  
> -config ARM_TEGRA20_DEVFREQ
> -	tristate "NVIDIA Tegra20 DEVFREQ Driver"
> -	depends on ARCH_TEGRA_2x_SOC || COMPILE_TEST
> -	depends on COMMON_CLK
> -	select DEVFREQ_GOV_SIMPLE_ONDEMAND
> -	help
> -	  This adds the DEVFREQ driver for the Tegra20 family of SoCs.
> -	  It reads Memory Controller counters and adjusts the operating
> -	  frequencies and voltages with OPP support.
> -
>  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 3ca1ad0ecb97..a16333ea7034 100644
> --- a/drivers/devfreq/Makefile
> +++ b/drivers/devfreq/Makefile
> @@ -13,7 +13,6 @@ obj-$(CONFIG_ARM_IMX_BUS_DEVFREQ)	+= imx-bus.o
>  obj-$(CONFIG_ARM_IMX8M_DDRC_DEVFREQ)	+= imx8m-ddrc.o
>  obj-$(CONFIG_ARM_RK3399_DMC_DEVFREQ)	+= rk3399_dmc.o
>  obj-$(CONFIG_ARM_TEGRA_DEVFREQ)		+= tegra30-devfreq.o
> -obj-$(CONFIG_ARM_TEGRA20_DEVFREQ)	+= tegra20-devfreq.o
>  
>  # DEVFREQ Event Drivers
>  obj-$(CONFIG_PM_DEVFREQ_EVENT)		+= event/
> diff --git a/drivers/devfreq/tegra20-devfreq.c b/drivers/devfreq/tegra20-devfreq.c
> deleted file mode 100644
> index fd801534771d..000000000000
> --- a/drivers/devfreq/tegra20-devfreq.c
> +++ /dev/null
> @@ -1,210 +0,0 @@
> -// SPDX-License-Identifier: GPL-2.0
> -/*
> - * NVIDIA Tegra20 devfreq driver
> - *
> - * Copyright (C) 2019 GRATE-DRIVER project
> - */
> -
> -#include <linux/clk.h>
> -#include <linux/devfreq.h>
> -#include <linux/io.h>
> -#include <linux/kernel.h>
> -#include <linux/module.h>
> -#include <linux/of_device.h>
> -#include <linux/platform_device.h>
> -#include <linux/pm_opp.h>
> -#include <linux/slab.h>
> -
> -#include <soc/tegra/mc.h>
> -
> -#include "governor.h"
> -
> -#define MC_STAT_CONTROL				0x90
> -#define MC_STAT_EMC_CLOCK_LIMIT			0xa0
> -#define MC_STAT_EMC_CLOCKS			0xa4
> -#define MC_STAT_EMC_CONTROL			0xa8
> -#define MC_STAT_EMC_COUNT			0xb8
> -
> -#define EMC_GATHER_CLEAR			(1 << 8)
> -#define EMC_GATHER_ENABLE			(3 << 8)
> -
> -struct tegra_devfreq {
> -	struct devfreq *devfreq;
> -	struct clk *emc_clock;
> -	void __iomem *regs;
> -};
> -
> -static int tegra_devfreq_target(struct device *dev, unsigned long *freq,
> -				u32 flags)
> -{
> -	struct tegra_devfreq *tegra = dev_get_drvdata(dev);
> -	struct devfreq *devfreq = tegra->devfreq;
> -	struct dev_pm_opp *opp;
> -	unsigned long rate;
> -	int err;
> -
> -	opp = devfreq_recommended_opp(dev, freq, flags);
> -	if (IS_ERR(opp))
> -		return PTR_ERR(opp);
> -
> -	rate = dev_pm_opp_get_freq(opp);
> -	dev_pm_opp_put(opp);
> -
> -	err = clk_set_min_rate(tegra->emc_clock, rate);
> -	if (err)
> -		return err;
> -
> -	err = clk_set_rate(tegra->emc_clock, 0);
> -	if (err)
> -		goto restore_min_rate;
> -
> -	return 0;
> -
> -restore_min_rate:
> -	clk_set_min_rate(tegra->emc_clock, devfreq->previous_freq);
> -
> -	return err;
> -}
> -
> -static int tegra_devfreq_get_dev_status(struct device *dev,
> -					struct devfreq_dev_status *stat)
> -{
> -	struct tegra_devfreq *tegra = dev_get_drvdata(dev);
> -
> -	/*
> -	 * EMC_COUNT returns number of memory events, that number is lower
> -	 * than the number of clocks. Conversion ratio of 1/8 results in a
> -	 * bit higher bandwidth than actually needed, it is good enough for
> -	 * the time being because drivers don't support requesting minimum
> -	 * needed memory bandwidth yet.
> -	 *
> -	 * TODO: adjust the ratio value once relevant drivers will support
> -	 * memory bandwidth management.
> -	 */
> -	stat->busy_time = readl_relaxed(tegra->regs + MC_STAT_EMC_COUNT);
> -	stat->total_time = readl_relaxed(tegra->regs + MC_STAT_EMC_CLOCKS) / 8;
> -	stat->current_frequency = clk_get_rate(tegra->emc_clock);
> -
> -	writel_relaxed(EMC_GATHER_CLEAR, tegra->regs + MC_STAT_CONTROL);
> -	writel_relaxed(EMC_GATHER_ENABLE, tegra->regs + MC_STAT_CONTROL);
> -
> -	return 0;
> -}
> -
> -static struct devfreq_dev_profile tegra_devfreq_profile = {
> -	.polling_ms	= 500,
> -	.target		= tegra_devfreq_target,
> -	.get_dev_status	= tegra_devfreq_get_dev_status,
> -};
> -
> -static struct tegra_mc *tegra_get_memory_controller(void)
> -{
> -	struct platform_device *pdev;
> -	struct device_node *np;
> -	struct tegra_mc *mc;
> -
> -	np = of_find_compatible_node(NULL, NULL, "nvidia,tegra20-mc-gart");
> -	if (!np)
> -		return ERR_PTR(-ENOENT);
> -
> -	pdev = of_find_device_by_node(np);
> -	of_node_put(np);
> -	if (!pdev)
> -		return ERR_PTR(-ENODEV);
> -
> -	mc = platform_get_drvdata(pdev);
> -	if (!mc)
> -		return ERR_PTR(-EPROBE_DEFER);
> -
> -	return mc;
> -}
> -
> -static int tegra_devfreq_probe(struct platform_device *pdev)
> -{
> -	struct tegra_devfreq *tegra;
> -	struct tegra_mc *mc;
> -	unsigned long max_rate;
> -	unsigned long rate;
> -	int err;
> -
> -	mc = tegra_get_memory_controller();
> -	if (IS_ERR(mc)) {
> -		err = PTR_ERR(mc);
> -		dev_err(&pdev->dev, "failed to get memory controller: %d\n",
> -			err);
> -		return err;
> -	}
> -
> -	tegra = devm_kzalloc(&pdev->dev, sizeof(*tegra), GFP_KERNEL);
> -	if (!tegra)
> -		return -ENOMEM;
> -
> -	/* EMC is a system-critical clock that is always enabled */
> -	tegra->emc_clock = devm_clk_get(&pdev->dev, "emc");
> -	if (IS_ERR(tegra->emc_clock))
> -		return dev_err_probe(&pdev->dev, PTR_ERR(tegra->emc_clock),
> -				     "failed to get emc clock\n");
> -
> -	tegra->regs = mc->regs;
> -
> -	max_rate = clk_round_rate(tegra->emc_clock, ULONG_MAX);
> -
> -	for (rate = 0; rate <= max_rate; rate++) {
> -		rate = clk_round_rate(tegra->emc_clock, rate);
> -
> -		err = dev_pm_opp_add(&pdev->dev, rate, 0);
> -		if (err) {
> -			dev_err(&pdev->dev, "failed to add opp: %d\n", err);
> -			goto remove_opps;
> -		}
> -	}
> -
> -	/*
> -	 * Reset statistic gathers state, select global bandwidth for the
> -	 * statistics collection mode and set clocks counter saturation
> -	 * limit to maximum.
> -	 */
> -	writel_relaxed(0x00000000, tegra->regs + MC_STAT_CONTROL);
> -	writel_relaxed(0x00000000, tegra->regs + MC_STAT_EMC_CONTROL);
> -	writel_relaxed(0xffffffff, tegra->regs + MC_STAT_EMC_CLOCK_LIMIT);
> -
> -	platform_set_drvdata(pdev, tegra);
> -
> -	tegra->devfreq = devfreq_add_device(&pdev->dev, &tegra_devfreq_profile,
> -					    DEVFREQ_GOV_SIMPLE_ONDEMAND, NULL);
> -	if (IS_ERR(tegra->devfreq)) {
> -		err = PTR_ERR(tegra->devfreq);
> -		goto remove_opps;
> -	}
> -
> -	return 0;
> -
> -remove_opps:
> -	dev_pm_opp_remove_all_dynamic(&pdev->dev);
> -
> -	return err;
> -}
> -
> -static int tegra_devfreq_remove(struct platform_device *pdev)
> -{
> -	struct tegra_devfreq *tegra = platform_get_drvdata(pdev);
> -
> -	devfreq_remove_device(tegra->devfreq);
> -	dev_pm_opp_remove_all_dynamic(&pdev->dev);
> -
> -	return 0;
> -}
> -
> -static struct platform_driver tegra_devfreq_driver = {
> -	.probe		= tegra_devfreq_probe,
> -	.remove		= tegra_devfreq_remove,
> -	.driver		= {
> -		.name	= "tegra20-devfreq",
> -	},
> -};
> -module_platform_driver(tegra_devfreq_driver);
> -
> -MODULE_ALIAS("platform:tegra20-devfreq");
> -MODULE_AUTHOR("Dmitry Osipenko <digetx@gmail.com>");
> -MODULE_DESCRIPTION("NVIDIA Tegra20 devfreq driver");
> -MODULE_LICENSE("GPL v2");
> 

Applied it. Thanks.

-- 
Best Regards,
Chanwoo Choi
Samsung Electronics