5.8. ioctl MEDIA_IOC_SETUP_LINK

5.8.1. Name

MEDIA_IOC_SETUP_LINK - Modify the properties of a link

5.8.2. Synopsis

MEDIA_IOC_SETUP_LINK

int ioctl(int fd, MEDIA_IOC_SETUP_LINK, struct media_link_desc *argp)

5.8.3. Arguments

fd

File descriptor returned by open().

argp

Pointer to struct media_link_desc.

5.8.4. 描述

To change link properties applications fill a struct media_link_desc with link identification information (source and sink pad) and the new requested link flags. They then call the MEDIA_IOC_SETUP_LINK ioctl with a pointer to that structure.

The only configurable property is the ENABLED link flag to enable/disable a link. Links marked with the IMMUTABLE link flag can not be enabled or disabled.

Link configuration has no side effect on other links. If an enabled link at the sink pad prevents the link from being enabled, the driver returns with an EBUSY error code.

Only links marked with the DYNAMIC link flag can be enabled/disabled while streaming media data. Attempting to enable or disable a streaming non-dynamic link will return an EBUSY error code.

If the specified link can't be found the driver returns with an EINVAL error code.

5.8.5. Return Value

On success 0 is returned, on error -1 and the errno variable is set appropriately. The generic error codes are described at the Generic Error Codes chapter.

EINVAL

The struct media_link_desc references a non-existing link, or the link is immutable and an attempt to modify its configuration was made.