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Diffstat (limited to 'Documentation/userspace-api/media/v4l/dev-subdev.rst')
| -rw-r--r-- | Documentation/userspace-api/media/v4l/dev-subdev.rst | 31 |
1 files changed, 28 insertions, 3 deletions
diff --git a/Documentation/userspace-api/media/v4l/dev-subdev.rst b/Documentation/userspace-api/media/v4l/dev-subdev.rst index 43988516acdd..0f9eda3187f3 100644 --- a/Documentation/userspace-api/media/v4l/dev-subdev.rst +++ b/Documentation/userspace-api/media/v4l/dev-subdev.rst @@ -506,6 +506,8 @@ source pads. subdev-formats +.. _subdev-routing: + Streams, multiplexed media pads and internal routing ---------------------------------------------------- @@ -527,9 +529,9 @@ the its sink pad and allows to route them individually to one of its source pads. Subdevice drivers that support multiplexed streams are compatible with -non-multiplexed subdev drivers, but, of course, require a routing configuration -where the link between those two types of drivers contains only a single -stream. +non-multiplexed subdev drivers. However, if the driver at the sink end of a link +does not support streams, then only stream 0 of source end may be captured. +There may be additional limitations specific to the sink device. Understanding streams ^^^^^^^^^^^^^^^^^^^^^ @@ -570,6 +572,29 @@ Any configurations of a stream within a pad, such as format or selections, are independent of similar configurations on other streams. This is subject to change in the future. +Device types and routing setup +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +Different kinds of sub-devices have differing behaviour for route activation, +depending on the hardware. In all cases, however, only routes that have the +``V4L2_SUBDEV_STREAM_FL_ACTIVE`` flag set are active. + +Devices generating the streams may allow enabling and disabling some of the +routes or have a fixed routing configuration. If the routes can be disabled, not +declaring the routes (or declaring them without +``VIDIOC_SUBDEV_STREAM_FL_ACTIVE`` flag set) in ``VIDIOC_SUBDEV_S_ROUTING`` will +disable the routes. ``VIDIOC_SUBDEV_S_ROUTING`` will still return such routes +back to the user in the routes array, with the ``V4L2_SUBDEV_STREAM_FL_ACTIVE`` +flag unset. + +Devices transporting the streams almost always have more configurability with +respect to routing. Typically any route between the sub-device's sink and source +pads is possible, and multiple routes (usually up to certain limited number) may +be active simultaneously. For such devices, no routes are created by the driver +and user-created routes are fully replaced when ``VIDIOC_SUBDEV_S_ROUTING`` is +called on the sub-device. Such newly created routes have the device's default +configuration for format and selection rectangles. + Configuring streams ^^^^^^^^^^^^^^^^^^^ |