From 670027c507e99521d416994a18a498def9ef2ea3 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Andr=C3=A9=20Fabian=20Silva=20Delgado?= Date: Sat, 22 Oct 2016 19:31:08 -0300 Subject: Linux-libre 4.8.3-gnu --- Documentation/DocBook/media/v4l/func-poll.xml | 142 -------------------------- 1 file changed, 142 deletions(-) delete mode 100644 Documentation/DocBook/media/v4l/func-poll.xml (limited to 'Documentation/DocBook/media/v4l/func-poll.xml') diff --git a/Documentation/DocBook/media/v4l/func-poll.xml b/Documentation/DocBook/media/v4l/func-poll.xml deleted file mode 100644 index 4c73f1152..000000000 --- a/Documentation/DocBook/media/v4l/func-poll.xml +++ /dev/null @@ -1,142 +0,0 @@ - - - V4L2 poll() - &manvol; - - - - v4l2-poll - Wait for some event on a file descriptor - - - - - #include <sys/poll.h> - - int poll - struct pollfd *ufds - unsigned int nfds - int timeout - - - - - - Description - - With the poll() function applications -can suspend execution until the driver has captured data or is ready -to accept data for output. - - When streaming I/O has been negotiated this function waits -until a buffer has been filled by the capture device and can be dequeued -with the &VIDIOC-DQBUF; ioctl. For output devices this function waits -until the device is ready to accept a new buffer to be queued up with -the &VIDIOC-QBUF; ioctl for display. When buffers are already in the outgoing -queue of the driver (capture) or the incoming queue isn't full (display) -the function returns immediately. - - On success poll() returns the number of -file descriptors that have been selected (that is, file descriptors -for which the revents field of the -respective pollfd structure is non-zero). -Capture devices set the POLLIN and -POLLRDNORM flags in the -revents field, output devices the -POLLOUT and POLLWRNORM -flags. When the function timed out it returns a value of zero, on -failure it returns -1 and the -errno variable is set appropriately. When the -application did not call &VIDIOC-STREAMON; the -poll() function succeeds, but sets the -POLLERR flag in the -revents field. When the -application has called &VIDIOC-STREAMON; for a capture device but hasn't -yet called &VIDIOC-QBUF;, the poll() function -succeeds and sets the POLLERR flag in the -revents field. For output devices this -same situation will cause poll() to succeed -as well, but it sets the POLLOUT and -POLLWRNORM flags in the revents -field. - - If an event occurred (see &VIDIOC-DQEVENT;) then -POLLPRI will be set in the revents -field and poll() will return. - - When use of the read() function has -been negotiated and the driver does not capture yet, the -poll function starts capturing. When that fails -it returns a POLLERR as above. Otherwise it waits -until data has been captured and can be read. When the driver captures -continuously (as opposed to, for example, still images) the function -may return immediately. - - When use of the write() function has -been negotiated and the driver does not stream yet, the -poll function starts streaming. When that fails -it returns a POLLERR as above. Otherwise it waits -until the driver is ready for a non-blocking -write() call. - - If the caller is only interested in events (just -POLLPRI is set in the events -field), then poll() will not -start streaming if the driver does not stream yet. This makes it -possible to just poll for events and not for buffers. - - All drivers implementing the read() or -write() function or streaming I/O must also -support the poll() function. - - For more details see the -poll() manual page. - - - - Return Value - - On success, poll() returns the number -structures which have non-zero revents -fields, or zero if the call timed out. On error --1 is returned, and the -errno variable is set appropriately: - - - - EBADF - - One or more of the ufds members -specify an invalid file descriptor. - - - - EBUSY - - The driver does not support multiple read or write -streams and the device is already in use. - - - - EFAULT - - ufds references an inaccessible -memory area. - - - - EINTR - - The call was interrupted by a signal. - - - - EINVAL - - The nfds argument is greater -than OPEN_MAX. - - - - - -- cgit v1.2.3