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media: imx7.rst: add documentation for i.MX7 media driver
Add rst document to describe the i.MX7 media driver and also a working example from the Warp7 board usage with a OV2680 sensor. Signed-off-by: Rui Miguel Silva <rui.silva@linaro.org> Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com> Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl> Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
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Rui Miguel Silva
Mauro Carvalho Chehab
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.. SPDX-License-Identifier: GPL-2.0
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i.MX7 Video Capture Driver
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==========================
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Introduction
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------------
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The i.MX7 contrary to the i.MX5/6 family does not contain an Image Processing
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Unit (IPU); because of that the capabilities to perform operations or
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manipulation of the capture frames are less feature rich.
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For image capture the i.MX7 has three units:
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- CMOS Sensor Interface (CSI)
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- Video Multiplexer
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- MIPI CSI-2 Receiver
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::
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|\
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MIPI Camera Input ---> MIPI CSI-2 --- > | \
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| \
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| M |
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| U | ------> CSI ---> Capture
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| X |
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| /
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Parallel Camera Input ----------------> | /
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|/
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For additional information, please refer to the latest versions of the i.MX7
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reference manual [#f1]_.
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Entities
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--------
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imx7-mipi-csi2
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--------------
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This is the MIPI CSI-2 receiver entity. It has one sink pad to receive the pixel
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data from MIPI CSI-2 camera sensor. It has one source pad, corresponding to the
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virtual channel 0. This module is compliant to previous version of Samsung
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D-phy, and supports two D-PHY Rx Data lanes.
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csi_mux
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-------
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This is the video multiplexer. It has two sink pads to select from either camera
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sensor with a parallel interface or from MIPI CSI-2 virtual channel 0. It has
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a single source pad that routes to the CSI.
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csi
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---
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The CSI enables the chip to connect directly to external CMOS image sensor. CSI
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can interface directly with Parallel and MIPI CSI-2 buses. It has 256 x 64 FIFO
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to store received image pixel data and embedded DMA controllers to transfer data
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from the FIFO through AHB bus.
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This entity has one sink pad that receives from the csi_mux entity and a single
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source pad that routes video frames directly to memory buffers. This pad is
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routed to a capture device node.
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Usage Notes
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-----------
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To aid in configuration and for backward compatibility with V4L2 applications
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that access controls only from video device nodes, the capture device interfaces
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inherit controls from the active entities in the current pipeline, so controls
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can be accessed either directly from the subdev or from the active capture
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device interface. For example, the sensor controls are available either from the
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sensor subdevs or from the active capture device.
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Warp7 with OV2680
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-----------------
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On this platform an OV2680 MIPI CSI-2 module is connected to the internal MIPI
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CSI-2 receiver. The following example configures a video capture pipeline with
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an output of 800x600, and BGGR 10 bit bayer format:
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.. code-block:: none
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# Setup links
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media-ctl -l "'ov2680 1-0036':0 -> 'imx7-mipi-csis.0':0[1]"
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media-ctl -l "'imx7-mipi-csis.0':1 -> 'csi_mux':1[1]"
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media-ctl -l "'csi_mux':2 -> 'csi':0[1]"
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media-ctl -l "'csi':1 -> 'csi capture':0[1]"
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# Configure pads for pipeline
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media-ctl -V "'ov2680 1-0036':0 [fmt:SBGGR10_1X10/800x600 field:none]"
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media-ctl -V "'csi_mux':1 [fmt:SBGGR10_1X10/800x600 field:none]"
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media-ctl -V "'csi_mux':2 [fmt:SBGGR10_1X10/800x600 field:none]"
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media-ctl -V "'imx7-mipi-csis.0':0 [fmt:SBGGR10_1X10/800x600 field:none]"
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media-ctl -V "'csi':0 [fmt:SBGGR10_1X10/800x600 field:none]"
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After this streaming can start. The v4l2-ctl tool can be used to select any of
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the resolutions supported by the sensor.
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.. code-block:: none
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root@imx7s-warp:~# media-ctl -p
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Media controller API version 4.17.0
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Media device information
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------------------------
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driver imx-media
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model imx-media
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serial
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bus info
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hw revision 0x0
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driver version 4.17.0
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Device topology
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- entity 1: csi (2 pads, 2 links)
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type V4L2 subdev subtype Unknown flags 0
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device node name /dev/v4l-subdev0
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pad0: Sink
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[fmt:SBGGR10_1X10/800x600 field:none]
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<- "csi_mux":2 [ENABLED]
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pad1: Source
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[fmt:SBGGR10_1X10/800x600 field:none]
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-> "csi capture":0 [ENABLED]
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- entity 4: csi capture (1 pad, 1 link)
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type Node subtype V4L flags 0
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device node name /dev/video0
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pad0: Sink
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<- "csi":1 [ENABLED]
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- entity 10: csi_mux (3 pads, 2 links)
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type V4L2 subdev subtype Unknown flags 0
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device node name /dev/v4l-subdev1
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pad0: Sink
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[fmt:unknown/0x0]
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pad1: Sink
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[fmt:unknown/800x600 field:none]
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<- "imx7-mipi-csis.0":1 [ENABLED]
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pad2: Source
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[fmt:unknown/800x600 field:none]
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-> "csi":0 [ENABLED]
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- entity 14: imx7-mipi-csis.0 (2 pads, 2 links)
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type V4L2 subdev subtype Unknown flags 0
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device node name /dev/v4l-subdev2
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pad0: Sink
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[fmt:SBGGR10_1X10/800x600 field:none]
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<- "ov2680 1-0036":0 [ENABLED]
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pad1: Source
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[fmt:SBGGR10_1X10/800x600 field:none]
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-> "csi_mux":1 [ENABLED]
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- entity 17: ov2680 1-0036 (1 pad, 1 link)
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type V4L2 subdev subtype Sensor flags 0
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device node name /dev/v4l-subdev3
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pad0: Source
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[fmt:SBGGR10_1X10/800x600 field:none]
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-> "imx7-mipi-csis.0":0 [ENABLED]
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References
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----------
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.. [#f1] https://www.nxp.com/docs/en/reference-manual/IMX7SRM.pdf
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@ -44,6 +44,7 @@ For more details see the file COPYING in the source distribution of Linux.
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davinci-vpbe
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fimc
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imx
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imx7
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ipu3
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ivtv
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max2175
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