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Diffstat (limited to 'Documentation/driver-api/media/tx-rx.rst')
| -rw-r--r-- | Documentation/driver-api/media/tx-rx.rst | 44 |
1 files changed, 27 insertions, 17 deletions
diff --git a/Documentation/driver-api/media/tx-rx.rst b/Documentation/driver-api/media/tx-rx.rst index 29d66a47b56e..0b8c9cde8ee4 100644 --- a/Documentation/driver-api/media/tx-rx.rst +++ b/Documentation/driver-api/media/tx-rx.rst @@ -49,12 +49,31 @@ Link frequency The :ref:`V4L2_CID_LINK_FREQ <v4l2-cid-link-freq>` control is used to tell the receiver the frequency of the bus (i.e. it is not the same as the symbol rate). -``.s_stream()`` callback -^^^^^^^^^^^^^^^^^^^^^^^^ +Drivers that do not have user-configurable link frequency should report it +through the ``.get_mbus_config()`` subdev pad operation, in the ``link_freq`` +field of struct v4l2_mbus_config, instead of through controls. + +Receiver drivers should use :c:func:`v4l2_get_link_freq` helper to obtain the +link frequency from the transmitter sub-device. + +``.enable_streams()`` and ``.disable_streams()`` callbacks +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ -The struct struct v4l2_subdev_video_ops->s_stream() callback is used by the -receiver driver to control the transmitter driver's streaming state. +The struct v4l2_subdev_pad_ops->enable_streams() and struct +v4l2_subdev_pad_ops->disable_streams() callbacks are used by the receiver driver +to control the transmitter driver's streaming state. These callbacks may not be +called directly, but by using ``v4l2_subdev_enable_streams()`` and +``v4l2_subdev_disable_streams()``. + +Stopping the transmitter +^^^^^^^^^^^^^^^^^^^^^^^^ +A transmitter stops sending the stream of images as a result of +calling the ``.disable_streams()`` callback. Some transmitters may stop the +stream at a frame boundary whereas others stop immediately, +effectively leaving the current frame unfinished. The receiver driver +should not make assumptions either way, but function properly in both +cases. CSI-2 transmitter drivers ------------------------- @@ -76,14 +95,15 @@ where * - link_freq - The value of the ``V4L2_CID_LINK_FREQ`` integer64 menu item. * - nr_of_lanes - - Number of data lanes used on the CSI-2 link. This can - be obtained from the OF endpoint configuration. + - Number of data lanes used on the CSI-2 link. * - 2 - Data is transferred on both rising and falling edge of the signal. * - bits_per_sample - Number of bits per sample. * - k - - 16 for D-PHY and 7 for C-PHY + - 16 for D-PHY and 7 for C-PHY. + +Information on whether D-PHY or C-PHY is used, and the value of ``nr_of_lanes``, can be obtained from the OF endpoint configuration. .. note:: @@ -122,13 +142,3 @@ device, so this should be only done when it is needed. Receiver drivers that do not need explicit LP-11 or LP-111 state setup are waived from calling the two callbacks. - -Stopping the transmitter -^^^^^^^^^^^^^^^^^^^^^^^^ - -A transmitter stops sending the stream of images as a result of -calling the ``.s_stream()`` callback. Some transmitters may stop the -stream at a frame boundary whereas others stop immediately, -effectively leaving the current frame unfinished. The receiver driver -should not make assumptions either way, but function properly in both -cases. |