Re: [PATCH v3 3/5] devfreq: exynos-bus: convert to use dev_pm_opp_set_rate()

From: Chanwoo Choi <cw00.choi@samsung.com>
To: k.konieczny@partner.samsung.com
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
	Marek Szyprowski <m.szyprowski@samsung.com>,
	Krzysztof Kozlowski <krzk@kernel.org>,
	Kukjin Kim <kgene@kernel.org>,
	Kyungmin Park <kyungmin.park@samsung.com>,
	Mark Rutland <mark.rutland@arm.com>,
	MyungJoo Ham <myungjoo.ham@samsung.com>,
	Nishanth Menon <nm@ti.com>, Rob Herring <robh+dt@kernel.org>,
	Stephen Boyd <sboyd@kernel.org>,
	Viresh Kumar <vireshk@kernel.org>,
	devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
	linux-samsung-soc@vger.kernel.org
Subject: Re: [PATCH v3 3/5] devfreq: exynos-bus: convert to use dev_pm_opp_set_rate()
Date: Thu, 25 Jul 2019 19:17:15 +0900	[thread overview]
Message-ID: <beb2455b-7f9e-35df-d524-01f4f51a1c62@samsung.com> (raw)
In-Reply-To: <20190719150535.15501-4-k.konieczny@partner.samsung.com>

Hi Kamil,

Looks good to me. But, I have some comment. Please check them.

After this patch, exynos_bus_target is perfectly same with
exynos_bus_passive_target. The exynos_bus_passive_target() could be removed.

On 19. 7. 20. 오전 12:05, k.konieczny@partner.samsung.com wrote:
> Reuse opp core code for setting bus clock and voltage. As a side
> effect this allow useage of coupled regulators feature (required

s/useage/usage ?

> for boards using Exynos5422/5800 SoCs) because dev_pm_opp_set_rate()
> uses regulator_set_voltage_triplet() for setting regulator voltage
> while the old code used regulator_set_voltage_tol() with fixed
> tolerance. This patch also removes no longer needed parsing of DT
> property "exynos,voltage-tolerance" (no Exynos devfreq DT node uses
> it).
> 
> Signed-off-by: Kamil Konieczny <k.konieczny@partner.samsung.com>
> ---
>  drivers/devfreq/exynos-bus.c | 143 +++++++++--------------------------
>  1 file changed, 37 insertions(+), 106 deletions(-)
> 
> diff --git a/drivers/devfreq/exynos-bus.c b/drivers/devfreq/exynos-bus.c
> index f391044aa39d..c2147b0912a0 100644
> --- a/drivers/devfreq/exynos-bus.c
> +++ b/drivers/devfreq/exynos-bus.c
> @@ -25,7 +25,6 @@
>  #include <linux/slab.h>
>  
>  #define DEFAULT_SATURATION_RATIO	40
> -#define DEFAULT_VOLTAGE_TOLERANCE	2
>  
>  struct exynos_bus {
>  	struct device *dev;
> @@ -37,9 +36,9 @@ struct exynos_bus {
>  
>  	unsigned long curr_freq;
>  
> -	struct regulator *regulator;
> +	struct opp_table *opp_table;
> +
>  	struct clk *clk;
> -	unsigned int voltage_tolerance;
>  	unsigned int ratio;
>  };
>  
> @@ -99,56 +98,23 @@ static int exynos_bus_target(struct device *dev, unsigned long *freq, u32 flags)
>  {
>  	struct exynos_bus *bus = dev_get_drvdata(dev);
>  	struct dev_pm_opp *new_opp;
> -	unsigned long old_freq, new_freq, new_volt, tol;
>  	int ret = 0;
>  
> -	/* Get new opp-bus instance according to new bus clock */
> +	/* Get correct frequency for bus. */
>  	new_opp = devfreq_recommended_opp(dev, freq, flags);
>  	if (IS_ERR(new_opp)) {
>  		dev_err(dev, "failed to get recommended opp instance\n");
>  		return PTR_ERR(new_opp);
>  	}
>  
> -	new_freq = dev_pm_opp_get_freq(new_opp);
> -	new_volt = dev_pm_opp_get_voltage(new_opp);
>  	dev_pm_opp_put(new_opp);
>  
> -	old_freq = bus->curr_freq;
> -
> -	if (old_freq == new_freq)
> -		return 0;
> -	tol = new_volt * bus->voltage_tolerance / 100;
> -
>  	/* Change voltage and frequency according to new OPP level */
>  	mutex_lock(&bus->lock);
> +	ret = dev_pm_opp_set_rate(dev, *freq);
> +	if (!ret)
> +		bus->curr_freq = *freq;
>  
> -	if (old_freq < new_freq) {
> -		ret = regulator_set_voltage_tol(bus->regulator, new_volt, tol);
> -		if (ret < 0) {
> -			dev_err(bus->dev, "failed to set voltage\n");
> -			goto out;
> -		}
> -	}
> -
> -	ret = clk_set_rate(bus->clk, new_freq);
> -	if (ret < 0) {
> -		dev_err(dev, "failed to change clock of bus\n");
> -		clk_set_rate(bus->clk, old_freq);
> -		goto out;
> -	}
> -
> -	if (old_freq > new_freq) {
> -		ret = regulator_set_voltage_tol(bus->regulator, new_volt, tol);
> -		if (ret < 0) {
> -			dev_err(bus->dev, "failed to set voltage\n");
> -			goto out;
> -		}
> -	}
> -	bus->curr_freq = new_freq;
> -
> -	dev_dbg(dev, "Set the frequency of bus (%luHz -> %luHz, %luHz)\n",
> -			old_freq, new_freq, clk_get_rate(bus->clk));
> -out:
>  	mutex_unlock(&bus->lock);
>  
>  	return ret;
> @@ -195,8 +161,8 @@ static void exynos_bus_exit(struct device *dev)
>  		dev_warn(dev, "failed to disable the devfreq-event devices\n");
>  
>  	clk_disable_unprepare(bus->clk);
> -	if (bus->regulator)
> -		regulator_disable(bus->regulator);
> +	if (bus->opp_table)
> +		dev_pm_opp_put_regulators(bus->opp_table);
>  
>  	dev_pm_opp_of_remove_table(dev);
>  }
> @@ -209,39 +175,23 @@ static int exynos_bus_passive_target(struct device *dev, unsigned long *freq,
>  {
>  	struct exynos_bus *bus = dev_get_drvdata(dev);
>  	struct dev_pm_opp *new_opp;
> -	unsigned long old_freq, new_freq;
> -	int ret = 0;
> +	int ret;
>  
> -	/* Get new opp-bus instance according to new bus clock */
> +	/* Get correct frequency for bus. */
>  	new_opp = devfreq_recommended_opp(dev, freq, flags);
>  	if (IS_ERR(new_opp)) {
>  		dev_err(dev, "failed to get recommended opp instance\n");
>  		return PTR_ERR(new_opp);
>  	}
>  
> -	new_freq = dev_pm_opp_get_freq(new_opp);
>  	dev_pm_opp_put(new_opp);
>  
> -	old_freq = bus->curr_freq;
> -
> -	if (old_freq == new_freq)
> -		return 0;
> -
>  	/* Change the frequency according to new OPP level */
>  	mutex_lock(&bus->lock);
> +	ret = dev_pm_opp_set_rate(dev, *freq);
> +	if (!ret)
> +		bus->curr_freq = *freq;
>  
> -	ret = clk_set_rate(bus->clk, new_freq);
> -	if (ret < 0) {
> -		dev_err(dev, "failed to set the clock of bus\n");
> -		goto out;
> -	}
> -
> -	*freq = new_freq;
> -	bus->curr_freq = new_freq;
> -
> -	dev_dbg(dev, "Set the frequency of bus (%luHz -> %luHz, %luHz)\n",
> -			old_freq, new_freq, clk_get_rate(bus->clk));
> -out:
>  	mutex_unlock(&bus->lock);
>  
>  	return ret;
> @@ -259,20 +209,9 @@ static int exynos_bus_parent_parse_of(struct device_node *np,
>  					struct exynos_bus *bus)
>  {
>  	struct device *dev = bus->dev;
> -	int i, ret, count, size;
> -
> -	/* Get the regulator to provide each bus with the power */
> -	bus->regulator = devm_regulator_get(dev, "vdd");
> -	if (IS_ERR(bus->regulator)) {
> -		dev_err(dev, "failed to get VDD regulator\n");
> -		return PTR_ERR(bus->regulator);
> -	}
> -
> -	ret = regulator_enable(bus->regulator);
> -	if (ret < 0) {
> -		dev_err(dev, "failed to enable VDD regulator\n");
> -		return ret;
> -	}
> +	struct opp_table *opp_table;
> +	const char *vdd = "vdd";
> +	int i, count, size;
>  
>  	/*
>  	 * Get the devfreq-event devices to get the current utilization of
> @@ -281,26 +220,29 @@ static int exynos_bus_parent_parse_of(struct device_node *np,
>  	count = devfreq_event_get_edev_count(dev);
>  	if (count < 0) {
>  		dev_err(dev, "failed to get the count of devfreq-event dev\n");
> -		ret = count;
> -		goto err_regulator;
> +		return count;
>  	}
> -	bus->edev_count = count;
>  
> +	bus->edev_count = count;
>  	size = sizeof(*bus->edev) * count;
>  	bus->edev = devm_kzalloc(dev, size, GFP_KERNEL);
> -	if (!bus->edev) {
> -		ret = -ENOMEM;
> -		goto err_regulator;
> -	}
> +	if (!bus->edev)
> +		return -ENOMEM;
>  
>  	for (i = 0; i < count; i++) {
>  		bus->edev[i] = devfreq_event_get_edev_by_phandle(dev, i);
> -		if (IS_ERR(bus->edev[i])) {
> -			ret = -EPROBE_DEFER;
> -			goto err_regulator;
> -		}
> +		if (IS_ERR(bus->edev[i]))
> +			return -EPROBE_DEFER;
> +	}
> +
> +	opp_table = dev_pm_opp_set_regulators(dev, &vdd, 1);
> +	if (IS_ERR(opp_table)) {
> +		i = PTR_ERR(opp_table);
> +		dev_err(dev, "failed to set regulators %d\n", i);
> +		return i;

Maybe, you just used the 'i' defined variable instead of adding
new variable. But, I think that you better to add new variable
like 'err' for the readability. Or, jut use the 'PTR_ERR(opp_table)'
directly without any additional variable.

>  	}
>  
> +	bus->opp_table = opp_table;

Add blank line. 

>  	/*
>  	 * Optionally, Get the saturation ratio according to Exynos SoC
>  	 * When measuring the utilization of each AXI bus with devfreq-event
> @@ -314,16 +256,7 @@ static int exynos_bus_parent_parse_of(struct device_node *np,
>  	if (of_property_read_u32(np, "exynos,saturation-ratio", &bus->ratio))
>  		bus->ratio = DEFAULT_SATURATION_RATIO;
>  
> -	if (of_property_read_u32(np, "exynos,voltage-tolerance",
> -					&bus->voltage_tolerance))
> -		bus->voltage_tolerance = DEFAULT_VOLTAGE_TOLERANCE;
> -
>  	return 0;
> -
> -err_regulator:
> -	regulator_disable(bus->regulator);
> -
> -	return ret;
>  }
>  
>  static int exynos_bus_parse_of(struct exynos_bus *bus)
> @@ -414,12 +347,8 @@ static int exynos_bus_probe(struct platform_device *pdev)
>  
>  	/* Parse the device-tree to get the resource information */
>  	ret = exynos_bus_parse_of(bus);
> -	if (ret < 0) {
> -		if (!passive)
> -			regulator_disable(bus->regulator);
> -
> -		return ret;
> -	}
> +	if (ret < 0)
> +		goto err_reg;
>  
>  	if (passive)
>  		goto passive;
> @@ -512,10 +441,12 @@ static int exynos_bus_probe(struct platform_device *pdev)
>  
>  err:
>  	clk_disable_unprepare(bus->clk);
> -	if (!passive)
> -		regulator_disable(bus->regulator);
> -
>  	dev_pm_opp_of_remove_table(dev);

This function removes the 'opp_table'. But, the below code
uses the 'opp_table' variable by dev_pm_opp_put_regulators().

To disable the regulator, you have to call dev_pm_opp_of_remove_table(dev)
after dev_pm_opp_put_regulators(bus->opp_table).

> +err_reg:
> +	if (bus->opp_table) {
> +		dev_pm_opp_put_regulators(bus->opp_table);
> +		bus->opp_table = NULL;
> +	}
>  
>  	return ret;
>  }
> 

-- 
Best Regards,
Chanwoo Choi
Samsung Electronics