Date:   Thu, 5 Nov 2020 11:22:11 +0900
From:   Chanwoo Choi <cw00.choi@...sung.com>
To:     Dmitry Osipenko <digetx@...il.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Georgi Djakov <georgi.djakov@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Peter De Schrijver <pdeschrijver@...dia.com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        Mikko Perttunen <cyndis@...si.fi>,
        Viresh Kumar <vireshk@...nel.org>,
        Peter Geis <pgwipeout@...il.com>,
        Nicolas Chauvet <kwizart@...il.com>,
        Krzysztof Kozlowski <krzk@...nel.org>
Cc:     linux-tegra@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        devicetree@...r.kernel.org
Subject: Re: [PATCH v7 45/47] PM / devfreq: tegra30: Support interconnect
 and OPPs from device-tree

Hi Dmitry,

On 11/5/20 1:49 AM, Dmitry Osipenko wrote:
> This patch moves ACTMON driver away from generating OPP table by itself,
> transitioning it to use the table which comes from device-tree. This
> change breaks compatibility with older device-trees in order to bring
> support for the interconnect framework to the driver. This is a mandatory
> change which needs to be done in order to implement interconnect-based
> memory DVFS. Users of legacy device-trees will get a message telling that
> theirs DT needs to be upgraded. Now ACTMON issues memory bandwidth request
> using dev_pm_opp_set_bw(), instead of driving EMC clock rate directly.
> 
> Tested-by: Peter Geis <pgwipeout@...il.com>
> Tested-by: Nicolas Chauvet <kwizart@...il.com>
> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
> ---
>  drivers/devfreq/tegra30-devfreq.c | 96 +++++++++++++++++--------------
>  1 file changed, 54 insertions(+), 42 deletions(-)
> 
> diff --git a/drivers/devfreq/tegra30-devfreq.c b/drivers/devfreq/tegra30-devfreq.c
> index 38cc0d014738..4db027ca17e1 100644
> --- a/drivers/devfreq/tegra30-devfreq.c
> +++ b/drivers/devfreq/tegra30-devfreq.c
> @@ -19,6 +19,8 @@
>  #include <linux/reset.h>
>  #include <linux/workqueue.h>
>  
> +#include <soc/tegra/fuse.h>
> +
>  #include "governor.h"
>  
>  #define ACTMON_GLB_STATUS					0x0
> @@ -155,6 +157,7 @@ struct tegra_devfreq_device {
>  
>  struct tegra_devfreq {
>  	struct devfreq		*devfreq;
> +	struct opp_table	*opp_table;
>  
>  	struct reset_control	*reset;
>  	struct clk		*clock;
> @@ -612,34 +615,19 @@ static void tegra_actmon_stop(struct tegra_devfreq *tegra)
>  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;
> +	int ret;
>  
>  	opp = devfreq_recommended_opp(dev, freq, flags);
>  	if (IS_ERR(opp)) {
>  		dev_err(dev, "Failed to find opp for %lu Hz\n", *freq);
>  		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 * KHZ);
> -	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);
> +	ret = dev_pm_opp_set_bw(dev, opp);
> +	dev_pm_opp_put(opp);
>  
> -	return err;
> +	return ret;
>  }
>  
>  static int tegra_devfreq_get_dev_status(struct device *dev,
> @@ -655,7 +643,7 @@ static int tegra_devfreq_get_dev_status(struct device *dev,
>  	stat->private_data = tegra;
>  
>  	/* The below are to be used by the other governors */
> -	stat->current_frequency = cur_freq;
> +	stat->current_frequency = cur_freq * KHZ;
>  
>  	actmon_dev = &tegra->devices[MCALL];
>  
> @@ -705,7 +693,12 @@ static int tegra_governor_get_target(struct devfreq *devfreq,
>  		target_freq = max(target_freq, dev->target_freq);
>  	}
>  
> -	*freq = target_freq;
> +	/*
> +	 * tegra-devfreq driver operates with KHz units, while OPP table
> +	 * entries use Hz units. Hence we need to convert the units for the
> +	 * devfreq core.
> +	 */
> +	*freq = target_freq * KHZ;
>  
>  	return 0;
>  }
> @@ -774,13 +767,22 @@ static struct devfreq_governor tegra_devfreq_governor = {
>  
>  static int tegra_devfreq_probe(struct platform_device *pdev)
>  {
> +	u32 hw_version = BIT(tegra_sku_info.soc_speedo_id);
>  	struct tegra_devfreq_device *dev;
>  	struct tegra_devfreq *tegra;
> +	struct opp_table *opp_table;
>  	struct devfreq *devfreq;
>  	unsigned int i;
>  	long rate;
>  	int err;
>  
> +	/* legacy device-trees don't have OPP table and must be updated */
> +	if (!device_property_present(&pdev->dev, "operating-points-v2")) {
> +		dev_err(&pdev->dev,
> +			"OPP table not found, please update your device tree\n");
> +		return -ENODEV;
> +	}
> +
>  	tegra = devm_kzalloc(&pdev->dev, sizeof(*tegra), GFP_KERNEL);
>  	if (!tegra)
>  		return -ENOMEM;
> @@ -822,11 +824,31 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
>  		return err;
>  	}
>  
> +	tegra->opp_table = dev_pm_opp_get_opp_table(&pdev->dev);
> +	err = PTR_ERR_OR_ZERO(tegra->opp_table);
> +	if (err) {
> +		dev_err(&pdev->dev, "Failed to prepare OPP table: %d\n", err);
> +		return err;
> +	}
> +
> +	opp_table = dev_pm_opp_set_supported_hw(&pdev->dev, &hw_version, 1);
> +	err = PTR_ERR_OR_ZERO(opp_table);
> +	if (err) {
> +		dev_err(&pdev->dev, "Failed to set supported HW: %d\n", err);
> +		goto put_table;
> +	}
> +
> +	err = dev_pm_opp_of_add_table(&pdev->dev);
> +	if (err) {
> +		dev_err(&pdev->dev, "Failed to add OPP table: %d\n", err);
> +		goto put_hw;
> +	}
> +
>  	err = clk_prepare_enable(tegra->clock);
>  	if (err) {
>  		dev_err(&pdev->dev,
>  			"Failed to prepare and enable ACTMON clock\n");
> -		return err;
> +		goto remove_table;
>  	}
>  
>  	err = reset_control_reset(tegra->reset);
> @@ -850,23 +872,6 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
>  		dev->regs = tegra->regs + dev->config->offset;
>  	}
>  
> -	for (rate = 0; rate <= tegra->max_freq * KHZ; rate++) {
> -		rate = clk_round_rate(tegra->emc_clock, rate);
> -
> -		if (rate < 0) {
> -			dev_err(&pdev->dev,
> -				"Failed to round clock rate: %ld\n", rate);
> -			err = rate;
> -			goto remove_opps;
> -		}
> -
> -		err = dev_pm_opp_add(&pdev->dev, rate / KHZ, 0);
> -		if (err) {
> -			dev_err(&pdev->dev, "Failed to add OPP: %d\n", err);
> -			goto remove_opps;
> -		}
> -	}
> -
>  	platform_set_drvdata(pdev, tegra);
>  
>  	tegra->clk_rate_change_nb.notifier_call = tegra_actmon_clk_notify_cb;
> @@ -882,7 +887,6 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
>  	}
>  
>  	tegra_devfreq_profile.initial_freq = clk_get_rate(tegra->emc_clock);
> -	tegra_devfreq_profile.initial_freq /= KHZ;
>  
>  	devfreq = devfreq_add_device(&pdev->dev, &tegra_devfreq_profile,
>  				     "tegra_actmon", NULL);
> @@ -902,6 +906,12 @@ static int tegra_devfreq_probe(struct platform_device *pdev)
>  	reset_control_reset(tegra->reset);
>  disable_clk:
>  	clk_disable_unprepare(tegra->clock);
> +remove_table:
> +	dev_pm_opp_of_remove_table(&pdev->dev);
> +put_hw:
> +	dev_pm_opp_put_supported_hw(tegra->opp_table);
> +put_table:
> +	dev_pm_opp_put_opp_table(tegra->opp_table);
>  
>  	return err;
>  }
> @@ -913,11 +923,13 @@ static int tegra_devfreq_remove(struct platform_device *pdev)
>  	devfreq_remove_device(tegra->devfreq);
>  	devfreq_remove_governor(&tegra_devfreq_governor);
>  
> -	dev_pm_opp_remove_all_dynamic(&pdev->dev);
> -
>  	reset_control_reset(tegra->reset);
>  	clk_disable_unprepare(tegra->clock);
>  
> +	dev_pm_opp_of_remove_table(&pdev->dev);
> +	dev_pm_opp_put_supported_hw(tegra->opp_table);
> +	dev_pm_opp_put_opp_table(tegra->opp_table);
> +
>  	return 0;
>  }
>  
> 

Acked-by: Chanwoo Choi <cw00.choi@...sung.com>

-- 
Best Regards,
Chanwoo Choi
Samsung Electronics

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