media-ioctl — Control a media device
#include <sys/ioctl.h>
int ioctl( | int fd, |
| int request, | |
void *argp); |
fdFile descriptor returned by open().
requestMedia ioctl request code as defined in the media.h header file, for example MEDIA_IOC_SETUP_LINK.
argpPointer to a request-specific structure.
The ioctl() function manipulates media device
parameters. The argument fd must be an open file
descriptor.
The ioctl request code specifies the media
function to be called. It has encoded in it whether the argument is an
input, output or read/write parameter, and the size of the argument
argp in bytes.
Macros and structures definitions specifying media ioctl requests and their parameters are located in the media.h header file. All media ioctl requests, their respective function and parameters are specified in Appendix F, Function Reference.
ioctl() returns 0 on
success. On failure, -1 is returned, and the
errno variable is set appropriately. Generic error codes
are listed below, and request-specific error codes are listed in the
individual requests descriptions.
When an ioctl that takes an output or read/write parameter fails, the parameter remains unmodified.
fd is not a valid open file descriptor.
argp references an inaccessible memory
area.
The request or the data pointed to by
argp is not valid. This is a very common error
code, see the individual ioctl requests listed in
Appendix F, Function Reference for actual causes.
Insufficient kernel memory was available to complete the request.
fd is not associated with a character
special device.