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Message-ID: <a762a6b6-a039-3b80-e1dc-edbc2ebcde7c@st.com>
Date: Wed, 24 Apr 2019 13:39:23 +0000
From: Benjamin GAIGNARD <benjamin.gaignard@...com>
To: "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
"agx@...xcpu.org" <agx@...xcpu.org>,
Yannick FERTRE <yannick.fertre@...com>
CC: "dmitry.torokhov@...il.com" <dmitry.torokhov@...il.com>,
"robh+dt@...nel.org" <robh+dt@...nel.org>,
"mark.rutland@....com" <mark.rutland@....com>,
"hadess@...ess.net" <hadess@...ess.net>,
"frowand.list@...il.com" <frowand.list@...il.com>,
"m.felsch@...gutronix.de" <m.felsch@...gutronix.de>,
"arnd@...db.de" <arnd@...db.de>,
"linux-input@...r.kernel.org" <linux-input@...r.kernel.org>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-stm32@...md-mailman.stormreply.com"
<linux-stm32@...md-mailman.stormreply.com>,
"broonie@...nel.org" <broonie@...nel.org>,
Linux PM <linux-pm@...r.kernel.org>
Subject: Re: [PATCH 1/5] of/device: Add of_ functions for
device_link_{add,remove}
On 4/24/19 3:06 PM, Rafael J. Wysocki wrote:
> On 4/24/2019 12:19 PM, Benjamin Gaignard wrote:
>> Allows to create and remove links between consumer and suppliers from
>> device-tree data. Use 'links-add' property from consumer node to setup
>> a link with a list of suppliers.
>
> One immediate question about this one is why stateless links are
> better here?
They aren't better, it is just because I wanted to keep one of_ function
for each related device_link_* functions.
>
>> Consumers will be suspend before their suppliers and resume after them.
>>
>> Add devm_of_device_links_add() to automatically remove the links
>> when the device is unbound from the bus.
>
> And this might not be necessary even with managed links.
I guess I could use DL_FLAG_PM_RUNTIME and DL_FLAG_AUTOREMOVE_CONSUMER
flags and just keep
of_device_links_add() but the naming will not be explicit.
>
>> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@...com>
>> ---
>> drivers/of/device.c | 103
>> ++++++++++++++++++++++++++++++++++++++++++++++
>> include/linux/of_device.h | 20 +++++++++
>> 2 files changed, 123 insertions(+)
>>
>> diff --git a/drivers/of/device.c b/drivers/of/device.c
>> index 3717f2a20d0d..011ba9bf7642 100644
>> --- a/drivers/of/device.c
>> +++ b/drivers/of/device.c
>> @@ -336,3 +336,106 @@ int of_device_uevent_modalias(struct device
>> *dev, struct kobj_uevent_env *env)
>> return 0;
>> }
>> EXPORT_SYMBOL_GPL(of_device_uevent_modalias);
>> +
>> +/**
>> + * of_device_links_add - Create links between consumer and suppliers
>> from
>> + * device tree data
>> + *
>> + * @consumer: consumer device
>> + *
>> + * Returns 0 on success, < 0 on failure.
>> + */
>> +int of_device_links_add(struct device *consumer)
>> +{
>> + struct device_node *np;
>> + struct platform_device *pdev;
>> + int i = 0;
>> +
>> + np = of_parse_phandle(consumer->of_node, "links-add", i++);
>> + while (np) {
>> + pdev = of_find_device_by_node(np);
>> + of_node_put(np);
>> + if (!pdev)
>> + return -EINVAL;
>> +
>> + device_link_add(consumer, &pdev->dev, DL_FLAG_STATELESS);
>> + platform_device_put(pdev);
>> +
>> + np = of_parse_phandle(consumer->of_node, "links-add", i++);
>> + }
>> +
>> + return 0;
>> +}
>> +EXPORT_SYMBOL_GPL(of_device_links_add);
>> +
>> +/**
>> + * of_device_links_remove - Remove links between consumer and
>> suppliers from
>> + * device tree data
>> + *
>> + * @consumer: consumer device
>> + *
>> + * Returns 0 on success, < 0 on failure.
>> + */
>> +int of_device_links_remove(struct device *consumer)
>> +{
>> + struct device_node *np;
>> + struct platform_device *pdev;
>> + int i = 0;
>> +
>> + np = of_parse_phandle(consumer->of_node, "links-add", i++);
>> + while (np) {
>> + pdev = of_find_device_by_node(np);
>> + of_node_put(np);
>> + if (!pdev)
>> + return -EINVAL;
>> +
>> + device_link_remove(consumer, &pdev->dev);
>> + platform_device_put(pdev);
>> +
>> + np = of_parse_phandle(consumer->of_node, "links-add", i++);
>> + }
>> +
>> + return 0;
>> +}
>> +EXPORT_SYMBOL_GPL(of_device_links_remove);
>> +
>> +static void devm_of_device_links_remove(struct device *dev, void *res)
>> +{
>> + of_device_links_remove(*(struct device **)res);
>> +}
>> +
>> +/**
>> + * devm_of_device_links_add - Create links between consumer and
>> suppliers
>> + * from device tree data
>> + *
>> + * @consumer: consumer device
>> + *
>> + * Returns 0 on success, < 0 on failure.
>> + *
>> + * Similar to of_device_links_add(), but will automatically call
>> + * of_device_links_remove() when the device is unbound from the bus.
>> + */
>> +int devm_of_device_links_add(struct device *consumer)
>> +{
>> + struct device **ptr;
>> + int ret;
>> +
>> + if (!consumer)
>> + return -EINVAL;
>> +
>> + ptr = devres_alloc(devm_of_device_links_remove,
>> + sizeof(*ptr), GFP_KERNEL);
>> + if (!ptr)
>> + return -ENOMEM;
>> +
>> + ret = of_device_links_add(consumer);
>> + if (ret < 0) {
>> + devres_free(ptr);
>> + } else {
>> + *ptr = consumer;
>> + devres_add(consumer, ptr);
>> + }
>> +
>> + return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(devm_of_device_links_add);
>> diff --git a/include/linux/of_device.h b/include/linux/of_device.h
>> index 8d31e39dd564..ad01db6828e8 100644
>> --- a/include/linux/of_device.h
>> +++ b/include/linux/of_device.h
>> @@ -41,6 +41,11 @@ extern int of_device_request_module(struct device
>> *dev);
>> extern void of_device_uevent(struct device *dev, struct
>> kobj_uevent_env *env);
>> extern int of_device_uevent_modalias(struct device *dev, struct
>> kobj_uevent_env *env);
>> +
>> +extern int of_device_links_add(struct device *consumer);
>> +extern int of_device_links_remove(struct device *consumer);
>> +extern int devm_of_device_links_add(struct device *consumer);
>> +
>> static inline void of_device_node_put(struct device *dev)
>> {
>> of_node_put(dev->of_node);
>> @@ -91,6 +96,21 @@ static inline int of_device_uevent_modalias(struct
>> device *dev,
>> return -ENODEV;
>> }
>> +static int of_device_links_add(struct device *consumer)
>> +{
>> + return 0;
>> +}
>> +
>> +static int of_device_links_remove(struct device *consumer)
>> +{
>> + return 0;
>> +}
>> +
>> +static int devm_of_device_links_add(struct device *consumer)
>> +{
>> + return 0;
>> +}
>> +
>> static inline void of_device_node_put(struct device *dev) { }
>> static inline const struct of_device_id *__of_match_device(
>
>
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