media/v4l/dev-subdev.rst

30 -  negotiate image formats on individual pads
77 .. _pad-level-formats:
79 Pad-level Formats
84     Pad-level formats are only applicable to very complex devices that
94 Image formats are typically negotiated on video capture and output
122 configured differently. Applications need to configure the formats at
130 negotiate formats on a per-pad basis.
134 formats. The pipeline is checked for formats mismatch at
147 Acceptable formats on pads can (and usually do) depend on a number of
148 external parameters, such as formats on other pads, active links, or
149 even controls. Finding a combination of formats on all pads in a video
151 formats enumeration only. A format negotiation mechanism is required.
158 a set of formats parameters that are not connected to the hardware
159 configuration. Modifying those 'try' formats leaves the device state
163 While not kept as part of the device state, try formats are stored in
178 Formats returned by the driver during a negotiation iteration are
182 (as long as external parameters, such as formats on other pads or links'
185 Drivers automatically propagate formats inside sub-devices. When a try
186 or active format is set on a pad, corresponding formats on other pads of
188 modify formats as required by the device. However, they should comply
191 -  Formats should be propagated from sink pads to source pads. Modifying
196    reset the scale factors to default values when sink pads formats are
198    source pads formats should be reset to the sink pads formats.
200 Formats are not propagated across links, as that would involve
203 explicitly with compatible formats. Identical formats on the two ends of
205 different formats matching device requirements as being compatible.
308    size and V4L2_MBUS_FMT_SGRBG8_1X8 media bus code. Formats on the
328 formats by setting the ``which`` argument to
329 ``V4L2_SUBDEV_FORMAT_ACTIVE``. Active formats are changed exactly as try
330 formats by drivers. To avoid modifying the hardware state during format
331 negotiation, applications should negotiate try formats first and then
332 modify the active settings using the try formats returned during the
353 As for pad formats, drivers store try and active rectangles for the
507     subdev-formats
554 Interaction between routes, streams, formats and selections
558 formats and selections from pads to (pad, stream) pairs. Besides the
559 usual pad, also the stream ID needs to be provided for setting formats and
560 selections. The order of configuring formats and selections along a stream is
588 setting the routing table will reset formats and selections in the
591 3) Configure formats and selections. Formats and selections of each stream
659 3) Configure formats and selections
661 After configuring routing, the next step is configuring the formats and