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Subject: Re: [PATCH v3 3/5] devfreq: exynos-bus: convert to use
 dev_pm_opp_set_rate()
To:     Chanwoo Choi <cw00.choi@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
From:   Kamil Konieczny <k.konieczny@partner.samsung.com>
Message-ID: <ed80b6e3-5b40-18ce-ca1e-65520edf516e@partner.samsung.com>
Date:   Thu, 25 Jul 2019 15:35:53 +0200
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Hi Chanwoo,

On 25.07.2019 12:17, Chanwoo Choi wrote:
> Hi Kamil,
> 
> Looks good to me. But, I have some comment. Please check them.

Thank you for review, please see answers below.

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

Ok, I will make it in separate patch to simplify review process.

> 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 ?

Good catch, I will change it.

>> 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.

I will remove not related changes, so here I will reuse 'ret' variable.

>>  	}
>>  
>> +	bus->opp_table = opp_table;
> 
> Add blank line. 

OK

>>  	/*
>>  	 * 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).

Regulators should be set before dev_pm_opp_add_table(), so exit sequence
should be in reverse order,

init order:

exynos_bus_parent_parse_of()
	dev_pm_opp_set_regulators()
exynos_bus_parse_of()
	clk_prepare_enable()
	dev_pm_opp_of_add_table()

exit or error order:

dev_pm_opp_of_remove_table()
clk_disable_unprepare()
if (bus->opp_table)
	dev_pm_opp_put_regulators(bus->opp_table);

I will send v4 soon.

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

-- 
Best regards,
Kamil Konieczny
Samsung R&D Institute Poland