linux-kernel - Re: [PATCH v2 02/11] PM / devfreq: Remove devfreq_get_devfreq_by

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Date:   Fri, 20 Dec 2019 01:40:42 +0000
From:   Leonard Crestez <leonard.crestez@....com>
To:     Chanwoo Choi <cw00.choi@...sung.com>,
        "krzk@...nel.org" <krzk@...nel.org>
CC:     "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "heiko@...ech.de" <heiko@...ech.de>,
        "lukasz.luba@....com" <lukasz.luba@....com>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "a.swigon@...sung.com" <a.swigon@...sung.com>,
        "m.szyprowski@...sung.com" <m.szyprowski@...sung.com>,
        "kgene@...nel.org" <kgene@...nel.org>,
        "myungjoo.ham@...sung.com" <myungjoo.ham@...sung.com>,
        "kyungmin.park@...sung.com" <kyungmin.park@...sung.com>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        "linux-samsung-soc@...r.kernel.org" 
        <linux-samsung-soc@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-rockchip@...ts.infradead.org" 
        <linux-rockchip@...ts.infradead.org>
Subject: Re: [PATCH v2 02/11] PM / devfreq: Remove
 devfreq_get_devfreq_by_phandle function

On 2019-12-20 2:54 AM, Chanwoo Choi wrote:
> On 12/20/19 9:46 AM, Leonard Crestez wrote:
>> On 20.12.2019 02:18, Chanwoo Choi wrote:
>>> Previously, devfreq core support 'devfreq' property in order to get
>>> the devfreq device by phandle. But, 'devfreq' property name is not proper
>>> on devicetree binding because this name doesn't mean the any h/w attribute.
>>>
>>> The devfreq core hand over the right to decide the property name
>>> for getting the devfreq device on devicetree. Each devfreq driver
>>> will decide the property name on devicetree binding and then get
>>> the devfreq device by using devfreq_get_devfreq_by_node().
>>>
>>> Signed-off-by: Chanwoo Choi <cw00.choi@...sung.com>
>>> ---
>>>    drivers/devfreq/devfreq.c    | 35 -----------------------------------
>>>    drivers/devfreq/exynos-bus.c | 12 +++++++++++-
>>>    include/linux/devfreq.h      |  8 --------
>>>    3 files changed, 11 insertions(+), 44 deletions(-)
>>>
>>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>>> index cb8ca81c8973..c3d3c7c802a0 100644
>>> --- a/drivers/devfreq/devfreq.c
>>> +++ b/drivers/devfreq/devfreq.c
>>> @@ -991,48 +991,13 @@ struct devfreq *devfreq_get_devfreq_by_node(struct device_node *node)
>>>    
>>>    	return ERR_PTR(-ENODEV);
>>>    }
>>> -
>>> -/*
>>> - * devfreq_get_devfreq_by_phandle - Get the devfreq device from devicetree
>>> - * @dev - instance to the given device
>>> - * @index - index into list of devfreq
>>> - *
>>> - * return the instance of devfreq device
>>> - */
>>> -struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev, int index)
>>> -{
>>> -	struct device_node *node;
>>> -	struct devfreq *devfreq;
>>> -
>>> -	if (!dev)
>>> -		return ERR_PTR(-EINVAL);
>>> -
>>> -	if (!dev->of_node)
>>> -		return ERR_PTR(-EINVAL);
>>> -
>>> -	node = of_parse_phandle(dev->of_node, "devfreq", index);
>>> -	if (!node)
>>> -		return ERR_PTR(-ENODEV);
>>> -
>>> -	devfreq = devfreq_get_devfreq_by_node(node);
>>> -	of_node_put(node);
>>> -
>>> -	return devfreq;
>>> -}
>>> -
>>>    #else
>>>    struct devfreq *devfreq_get_devfreq_by_node(struct device_node *node)
>>>    {
>>>    	return ERR_PTR(-ENODEV);
>>>    }
>>> -
>>> -struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev, int index)
>>> -{
>>> -	return ERR_PTR(-ENODEV);
>>> -}
>>>    #endif /* CONFIG_OF */
>>>    EXPORT_SYMBOL_GPL(devfreq_get_devfreq_by_node);
>>> -EXPORT_SYMBOL_GPL(devfreq_get_devfreq_by_phandle);
>>>    
>>>    /**
>>>     * devm_devfreq_remove_device() - Resource-managed devfreq_remove_device()
>>> diff --git a/drivers/devfreq/exynos-bus.c b/drivers/devfreq/exynos-bus.c
>>> index 7f5917d59072..1bc4e3c81115 100644
>>> --- a/drivers/devfreq/exynos-bus.c
>>> +++ b/drivers/devfreq/exynos-bus.c
>>> @@ -86,6 +86,16 @@ static int exynos_bus_get_event(struct exynos_bus *bus,
>>>    	return ret;
>>>    }
>>>    
>>> +static struct devfreq *exynos_bus_get_parent_devfreq(struct device_node *np)
>>> +{
>>> +	struct device_node *node = of_parse_phandle(np, "devfreq", 0);
>>> +
>>> +	if (!node)
>>> +		return ERR_PTR(-ENODEV);
>>> +
>>> +	return devfreq_get_devfreq_by_node(node);
>>
>> You need to call of_node_put(node) here and in several other places.
>>
>> The old devfreq_get_devfreq_by_phandle API handled this internally but
>> devfreq_get_devfreq_by_node doesn't.
> 
> Thanks. I'll fix it.
> 
>>
>> Maybe the _by_phandle API could be kept and just take the property name
>> instead of always using "devfreq"?
> 
> Do you mean like below?
> devfreq_get_devfreq_by_phandle(struct device *dev, int index)
> -> devfreq_get_devfreq_by_phandle(struct device *dev, char *property_name, int index)
> 
> In case of devfreq-event.c,
> struct devfreq_event_dev *devfreq_event_get_edev_by_phandle(
> 						struct device *dev,
> 						char property_name,
> 						int index)
> int devfreq_event_get_edev_count(struct device *dev, char *property_name)

Yes. These helpers would avoid the need for explicit of_node_put.

> 
>>
>>> +}
>>> +
>>>    /*
>>>     * devfreq function for both simple-ondemand and passive governor
>>>     */
>>> @@ -353,7 +363,7 @@ static int exynos_bus_profile_init_passive(struct exynos_bus *bus,
>>>    	profile->exit = exynos_bus_passive_exit;
>>>    
>>>    	/* Get the instance of parent devfreq device */
>>> -	parent_devfreq = devfreq_get_devfreq_by_phandle(dev, 0);
>>> +	parent_devfreq = exynos_bus_get_parent_devfreq(dev->of_node);
>>>    	if (IS_ERR(parent_devfreq))
>>>    		return -EPROBE_DEFER;
>>>    
>>> diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
>>> index 1dccc47acbce..a4351698fb64 100644
>>> --- a/include/linux/devfreq.h
>>> +++ b/include/linux/devfreq.h
>>> @@ -254,8 +254,6 @@ extern void devm_devfreq_unregister_notifier(struct device *dev,
>>>    				struct notifier_block *nb,
>>>    				unsigned int list);
>>>    extern struct devfreq *devfreq_get_devfreq_by_node(struct device_node *node);
>>> -extern struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev,
>>> -						int index);
>>>    
>>>    #if IS_ENABLED(CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND)
>>>    /**
>>> @@ -413,12 +411,6 @@ static inline struct devfreq *devfreq_get_devfreq_by_node(struct device_node *no
>>>    	return ERR_PTR(-ENODEV);
>>>    }
>>>    
>>> -static inline struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev,
>>> -							int index)
>>> -{
>>> -	return ERR_PTR(-ENODEV);
>>> -}
>>> -
>>>    static inline int devfreq_update_stats(struct devfreq *df)
>>>    {
>>>    	return -EINVAL;