From 8d4f9d241cdbd71a882a852c6e9285de279c0f87 Mon Sep 17 00:00:00 2001 From: Hans Verkuil Date: Sun, 18 Jan 2009 13:00:12 +0100 Subject: v4l2spec: add version 0.24 of the spec From: Hans Verkuil Priority: normal Signed-off-by: Hans Verkuil --- v4l2-spec/func-write.sgml | 136 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 136 insertions(+) create mode 100644 v4l2-spec/func-write.sgml (limited to 'v4l2-spec/func-write.sgml') diff --git a/v4l2-spec/func-write.sgml b/v4l2-spec/func-write.sgml new file mode 100644 index 000000000..2c09c0937 --- /dev/null +++ b/v4l2-spec/func-write.sgml @@ -0,0 +1,136 @@ + + + V4L2 write() + &manvol; + + + + v4l2-write + Write to a V4L2 device + + + + + #include <unistd.h> + + ssize_t write + int fd + void *buf + size_t count + + + + + + Arguments + + + + fd + + &fd; + + + + buf + + + + + + count + + + + + + + + + Description + + write() writes up to +count bytes to the device referenced by the +file descriptor fd from the buffer starting at +buf. When the hardware outputs are not active +yet, this function enables them. When count is +zero, write() returns +0 without any other effect. + + When the application does not provide more data in time, the +previous video frame, raw VBI image, sliced VPS or WSS data is +displayed again. Sliced Teletext or Closed Caption data is not +repeated, the driver inserts a blank line instead. + + + + Return Value + + On success, the number of bytes written are returned. Zero +indicates nothing was written. On error, -1 +is returned, and the errno variable is set +appropriately. In this case the next write will start at the beginning +of a new frame. Possible error codes are: + + + + EAGAIN + + Non-blocking I/O has been selected using the O_NONBLOCK flag and no +buffer space was available to write the data immediately. + + + + EBADF + + fd is not a valid file +descriptor or is not open for writing. + + + + EBUSY + + The driver does not support multiple write streams and the +device is already in use. + + + + EFAULT + + buf references an inaccessible +memory area. + + + + EINTR + + The call was interrupted by a signal before any +data was written. + + + + EIO + + I/O error. This indicates some hardware problem. + + + + EINVAL + + The write() function is not +supported by this driver, not on this device, or generally not on this +type of device. + + + + + + + -- cgit v1.2.3