2.22. V4L2 async kAPI¶

enum v4l2_async_match_type¶: type of asynchronous subdevice logic to be used in order to identify a match

Constants

V4L2_ASYNC_MATCH_TYPE_I2C: Match will check for I2C adapter ID and address
V4L2_ASYNC_MATCH_TYPE_FWNODE: Match will use firmware node

Description

This enum is used by the asynchronous connection logic to define the algorithm that will be used to match an asynchronous device.

struct v4l2_async_match_desc¶: async connection match information

Definition:

struct v4l2_async_match_desc {
    enum v4l2_async_match_type type;
    union {
        struct fwnode_handle *fwnode;
        struct {
            int adapter_id;
            unsigned short address;
        } i2c;
    };
};

Members

type: type of match that will be used
{unnamed_union}: anonymous
fwnode: pointer to struct fwnode_handle to be matched. Used if match_type is V4L2_ASYNC_MATCH_TYPE_FWNODE.
i2c: embedded struct with I2C parameters to be matched. Both match.i2c.adapter_id and match.i2c.address should be matched. Used if match_type is V4L2_ASYNC_MATCH_TYPE_I2C.

i2c.adapter_id

I2C adapter ID to be matched. Used if match_type is V4L2_ASYNC_MATCH_TYPE_I2C.

i2c.address

I2C address to be matched. Used if match_type is V4L2_ASYNC_MATCH_TYPE_I2C.

struct v4l2_async_connection¶: sub-device connection descriptor, as known to a bridge

Definition:

struct v4l2_async_connection {
    struct v4l2_async_match_desc match;
    struct v4l2_async_notifier *notifier;
    struct list_head asc_entry;
    struct list_head asc_subdev_entry;
    struct v4l2_subdev *sd;
};

Members

match: struct of match type and per-bus type matching data sets
notifier: the async notifier the connection is related to
asc_entry: used to add struct v4l2_async_connection objects to the notifier waiting_list or done_list
asc_subdev_entry: entry in struct v4l2_async_subdev.asc_list list
sd: the related sub-device

Description

When this struct is used as a member in a driver specific struct, the driver specific struct shall contain the struct v4l2_async_connection as its first member.

struct v4l2_async_notifier_operations¶: Asynchronous V4L2 notifier operations

Definition:

struct v4l2_async_notifier_operations {
    int (*bound)(struct v4l2_async_notifier *notifier,struct v4l2_subdev *subdev, struct v4l2_async_connection *asc);
    int (*complete)(struct v4l2_async_notifier *notifier);
    void (*unbind)(struct v4l2_async_notifier *notifier,struct v4l2_subdev *subdev, struct v4l2_async_connection *asc);
    void (*destroy)(struct v4l2_async_connection *asc);
};

Members

bound: a sub-device has been bound by the given connection
complete: All connections have been bound successfully. The complete callback is only executed for the root notifier.
unbind: a subdevice is leaving
destroy: the asc is about to be freed

struct v4l2_async_notifier¶: v4l2_device notifier data

Definition:

struct v4l2_async_notifier {
    const struct v4l2_async_notifier_operations *ops;
    struct v4l2_device *v4l2_dev;
    struct v4l2_subdev *sd;
    struct v4l2_async_notifier *parent;
    struct list_head waiting_list;
    struct list_head done_list;
    struct list_head notifier_entry;
};

Members

ops: notifier operations
v4l2_dev: v4l2_device of the root notifier, NULL otherwise
sd: sub-device that registered the notifier, NULL otherwise
parent: parent notifier
waiting_list: list of struct v4l2_async_connection, waiting for their drivers
done_list: list of struct v4l2_subdev, already probed
notifier_entry: member in a global list of notifiers

struct v4l2_async_subdev_endpoint¶: Entry in sub-device’s fwnode list

Definition:

struct v4l2_async_subdev_endpoint {
    struct list_head async_subdev_endpoint_entry;
    struct fwnode_handle *endpoint;
};

Members

async_subdev_endpoint_entry: An entry in async_subdev_endpoint_list of struct v4l2_subdev
endpoint: Endpoint fwnode agains which to match the sub-device

void v4l2_async_debug_init(struct dentry *debugfs_dir)¶: Initialize debugging tools.

Parameters

struct dentry *debugfs_dir: pointer to the parent debugfs struct dentry

void v4l2_async_nf_init(struct v4l2_async_notifier *notifier, struct v4l2_device *v4l2_dev)¶: Initialize a notifier.

Parameters

struct v4l2_async_notifier *notifier: pointer to struct v4l2_async_notifier
struct v4l2_device *v4l2_dev: pointer to struct v4l2_device

Description

This function initializes the notifier asc_entry. It must be called before adding a subdevice to a notifier, using one of: v4l2_async_nf_add_fwnode_remote(), v4l2_async_nf_add_fwnode() or v4l2_async_nf_add_i2c().

void v4l2_async_subdev_nf_init(struct v4l2_async_notifier *notifier, struct v4l2_subdev *sd)¶: Initialize a sub-device notifier.

Parameters

struct v4l2_async_notifier *notifier: pointer to struct v4l2_async_notifier
struct v4l2_subdev *sd: pointer to struct v4l2_subdev

Description

This function initializes the notifier asc_list. It must be called before adding a subdevice to a notifier, using one of: v4l2_async_nf_add_fwnode_remote(), v4l2_async_nf_add_fwnode() or v4l2_async_nf_add_i2c().

v4l2_async_nf_add_fwnode¶

v4l2_async_nf_add_fwnode (notifier, fwnode, type)

Allocate and add a fwnode async subdev to the notifier’s master asc_list.

Parameters

notifier: pointer to struct v4l2_async_notifier
fwnode: fwnode handle of the sub-device to be matched, pointer to struct fwnode_handle
type: Type of the driver’s async sub-device or connection struct. The struct v4l2_async_connection shall be the first member of the driver’s async struct, i.e. both begin at the same memory address.

Description

Allocate a fwnode-matched asc of size asc_struct_size, and add it to the notifiers asc_list. The function also gets a reference of the fwnode which is released later at notifier cleanup time.

v4l2_async_nf_add_fwnode_remote¶

v4l2_async_nf_add_fwnode_remote (notifier, ep, type)

Allocate and add a fwnode remote async subdev to the notifier’s master asc_list.

Parameters

notifier: pointer to struct v4l2_async_notifier
ep: local endpoint pointing to the remote connection to be matched, pointer to struct fwnode_handle
type: Type of the driver’s async connection struct. The struct v4l2_async_connection shall be the first member of the driver’s async connection struct, i.e. both begin at the same memory address.

Description

Gets the remote endpoint of a given local endpoint, set it up for fwnode matching and adds the async connection to the notifier’s asc_list. The function also gets a reference of the fwnode which is released later at notifier cleanup time.

This is just like v4l2_async_nf_add_fwnode(), but with the exception that the fwnode refers to a local endpoint, not the remote one.

v4l2_async_nf_add_i2c¶

v4l2_async_nf_add_i2c (notifier, adapter, address, type)

Allocate and add an i2c async subdev to the notifier’s master asc_list.

Parameters

notifier: pointer to struct v4l2_async_notifier
adapter: I2C adapter ID to be matched
address: I2C address of connection to be matched
type: Type of the driver’s async connection struct. The struct v4l2_async_connection shall be the first member of the driver’s async connection struct, i.e. both begin at the same memory address.

Description

Same as v4l2_async_nf_add_fwnode() but for I2C matched connections.

int v4l2_async_subdev_endpoint_add(struct v4l2_subdev *sd, struct fwnode_handle *fwnode)¶: Add an endpoint fwnode to async sub-device matching list

Parameters

struct v4l2_subdev *sd: the sub-device
struct fwnode_handle *fwnode: the endpoint fwnode to match

Description

Add a fwnode to the async sub-device’s matching list. This allows registering multiple async sub-devices from a single device.

Note that calling v4l2_subdev_cleanup() as part of the sub-device’s cleanup if endpoints have been added to the sub-device’s fwnode matching list.

Returns an error on failure, 0 on success.

struct v4l2_async_connection *v4l2_async_connection_unique(struct v4l2_subdev *sd)¶: return a unique struct v4l2_async_connection for a sub-device

Parameters

struct v4l2_subdev *sd: the sub-device

Description

Return an async connection for a sub-device, when there is a single one only.

int v4l2_async_nf_register(struct v4l2_async_notifier *notifier)¶: registers a subdevice asynchronous notifier

Parameters

struct v4l2_async_notifier *notifier: pointer to struct v4l2_async_notifier

void v4l2_async_nf_unregister(struct v4l2_async_notifier *notifier)¶: unregisters a subdevice asynchronous notifier

Parameters

struct v4l2_async_notifier *notifier: pointer to struct v4l2_async_notifier

void v4l2_async_nf_cleanup(struct v4l2_async_notifier *notifier)¶: clean up notifier resources

Parameters

struct v4l2_async_notifier *notifier: the notifier the resources of which are to be cleaned up

Description

Release memory resources related to a notifier, including the async connections allocated for the purposes of the notifier but not the notifier itself. The user is responsible for calling this function to clean up the notifier after calling v4l2_async_nf_add_fwnode_remote(), v4l2_async_nf_add_fwnode() or v4l2_async_nf_add_i2c().

There is no harm from calling v4l2_async_nf_cleanup() in other cases as long as its memory has been zeroed after it has been allocated.

v4l2_async_register_subdev¶

v4l2_async_register_subdev (sd)

registers a sub-device to the asynchronous subdevice framework

Parameters

sd: pointer to struct v4l2_subdev

int v4l2_async_register_subdev_sensor(struct v4l2_subdev *sd)¶: registers a sensor sub-device to the asynchronous sub-device framework and parse set up common sensor related devices

Parameters

struct v4l2_subdev *sd: pointer to struct v4l2_subdev

Description

This function is just like v4l2_async_register_subdev() with the exception that calling it will also parse firmware interfaces for remote references using v4l2_async_nf_parse_fwnode_sensor() and registers the async sub-devices. The sub-device is similarly unregistered by calling v4l2_async_unregister_subdev().

While registered, the subdev module is marked as in-use.

An error is returned if the module is no longer loaded on any attempts to register it.

void v4l2_async_unregister_subdev(struct v4l2_subdev *sd)¶: unregisters a sub-device to the asynchronous subdevice framework

Parameters

struct v4l2_subdev *sd: pointer to struct v4l2_subdev

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2.22. V4L2 async kAPI¶