Documentation/media/uapi/cec/cec-ioc-adap-g-phys-addr.rst

   1 .. -*- coding: utf-8; mode: rst -*-
   2
   3 .. _CEC_ADAP_PHYS_ADDR:
   4 .. _CEC_ADAP_G_PHYS_ADDR:
   5 .. _CEC_ADAP_S_PHYS_ADDR:
   6
   7 ************************************************
   8 ioctl CEC_ADAP_G_PHYS_ADDR, CEC_ADAP_S_PHYS_ADDR
   9 ************************************************
  10
  11 Name
  12 ====
  13
  14 CEC_ADAP_G_PHYS_ADDR, CEC_ADAP_S_PHYS_ADDR - Get or set the physical address
  15
  16
  17 Synopsis
  18 ========
  19
  20 .. cpp:function:: int ioctl( int fd, int request, __u16 *argp )
  21
  22 Arguments
  23 =========
  24
  25 ``fd``
  26     File descriptor returned by :ref:`open() <cec-func-open>`.
  27
  28 ``request``
  29     CEC_ADAP_G_PHYS_ADDR, CEC_ADAP_S_PHYS_ADDR
  30
  31 ``argp``
  32
  33
  34 Description
  35 ===========
  36
  37 .. note:: This documents the proposed CEC API. This API is not yet finalized
  38    and is currently only available as a staging kernel module.
  39
  40 To query the current physical address applications call the
  41 :ref:`CEC_ADAP_G_PHYS_ADDR` ioctl with a pointer to an __u16 where the
  42 driver stores the physical address.
  43
  44 To set a new physical address applications store the physical address in
  45 an __u16 and call the :ref:`CEC_ADAP_S_PHYS_ADDR` ioctl with a pointer to
  46 this integer. :ref:`CEC_ADAP_S_PHYS_ADDR` is only available if
  47 ``CEC_CAP_PHYS_ADDR`` is set (ENOTTY error code will be returned
  48 otherwise). :ref:`CEC_ADAP_S_PHYS_ADDR` can only be called by a file handle
  49 in initiator mode (see :ref:`CEC_S_MODE`), if not
  50 EBUSY error code will be returned.
  51
  52 The physical address is a 16-bit number where each group of 4 bits
  53 represent a digit of the physical address a.b.c.d where the most
  54 significant 4 bits represent 'a'. The CEC root device (usually the TV)
  55 has address 0.0.0.0. Every device that is hooked up to an input of the
  56 TV has address a.0.0.0 (where 'a' is ≥ 1), devices hooked up to those in
  57 turn have addresses a.b.0.0, etc. So a topology of up to 5 devices deep
  58 is supported. The physical address a device shall use is stored in the
  59 EDID of the sink.
  60
  61 For example, the EDID for each HDMI input of the TV will have a
  62 different physical address of the form a.0.0.0 that the sources will
  63 read out and use as their physical address.
  64
  65
  66 Return Value
  67 ============
  68
  69 On success 0 is returned, on error -1 and the ``errno`` variable is set
  70 appropriately. The generic error codes are described at the
  71 :ref:`Generic Error Codes <gen-errors>` chapter.