Orange Pi5 kernel

^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  1) .. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  2) .. c:namespace:: CEC
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  3) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  4) .. _cec-func-poll:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  5) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  6) **********
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  7) cec poll()
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  8) **********
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  9) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10) Name
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11) ====
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13) cec-poll - Wait for some event on a file descriptor
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15) Synopsis
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16) ========
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18) .. code-block:: c
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20)     #include <sys/poll.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22) .. c:function:: int poll( struct pollfd *ufds, unsigned int nfds, int timeout )
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) Arguments
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25) =========
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27) ``ufds``
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28)    List of FD events to be watched
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30) ``nfds``
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31)    Number of FD events at the \*ufds array
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33) ``timeout``
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34)    Timeout to wait for events
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36) Description
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37) ===========
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39) With the :c:func:`poll()` function applications can wait for CEC
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40) events.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42) On success :c:func:`poll()` returns the number of file descriptors
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43) that have been selected (that is, file descriptors for which the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44) ``revents`` field of the respective struct :c:type:`pollfd`
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45) is non-zero). CEC devices set the ``POLLIN`` and ``POLLRDNORM`` flags in
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46) the ``revents`` field if there are messages in the receive queue. If the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 47) transmit queue has room for new messages, the ``POLLOUT`` and
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 48) ``POLLWRNORM`` flags are set. If there are events in the event queue,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 49) then the ``POLLPRI`` flag is set. When the function times out it returns
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 50) a value of zero, on failure it returns -1 and the ``errno`` variable is
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 51) set appropriately.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 52) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 53) For more details see the :c:func:`poll()` manual page.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 54) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 55) Return Value
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 56) ============
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 57) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 58) On success, :c:func:`poll()` returns the number structures which have
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 59) non-zero ``revents`` fields, or zero if the call timed out. On error -1
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 60) is returned, and the ``errno`` variable is set appropriately:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 61) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 62) ``EBADF``
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 63)     One or more of the ``ufds`` members specify an invalid file
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 64)     descriptor.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 65) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 66) ``EFAULT``
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 67)     ``ufds`` references an inaccessible memory area.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 68) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 69) ``EINTR``
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 70)     The call was interrupted by a signal.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 71) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 72) ``EINVAL``
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 73)     The ``nfds`` value exceeds the ``RLIMIT_NOFILE`` value. Use
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 74)     ``getrlimit()`` to obtain this value.