[PATCH v2 3/6] media: admin-guide: Add starfive_camss.rst for Starfive Camera Subsystem

[Jack Zhu]

Add the file 'starfive_camss.rst' that documents the Starfive Camera
Subsystem driver which is used for handing image sensor data.

Signed-off-by: Jack Zhu <jack.zhu@xxxxxxxxxxxxxxxx>
---
 .../admin-guide/media/starfive_camss.rst      | 68 +++++++++++++++++++
 .../media/starfive_camss_graph.dot            | 28 ++++++++
 .../admin-guide/media/v4l-drivers.rst         |  1 +
 3 files changed, 97 insertions(+)
 create mode 100644 Documentation/admin-guide/media/starfive_camss.rst
 create mode 100644 Documentation/admin-guide/media/starfive_camss_graph.dot

diff --git a/Documentation/admin-guide/media/starfive_camss.rst b/Documentation/admin-guide/media/starfive_camss.rst
new file mode 100644
index 000000000000..12c5ebf794b8
--- /dev/null
+++ b/Documentation/admin-guide/media/starfive_camss.rst
@@ -0,0 +1,68 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+.. include:: <isonum.txt>
+
+================================
+Starfive Camera Subsystem driver
+================================
+
+Introduction
+------------
+
+This file documents the driver for the Starfive Camera Subsystem found on
+Starfive JH7110 SoC. The driver is located under drivers/media/platform/starfive.
+
+The driver implements V4L2, Media controller and v4l2_subdev interfaces.
+Camera sensor using V4L2 subdev interface in the kernel is supported.
+
+The driver has been successfully used on the Gstreamer 1.18.5 with
+v4l2src plugin.
+
+
+Starfive Camera Subsystem hardware
+----------------------------------
+
+The Starfive Camera Subsystem hardware consists of:
+
+- MIPI DPHY Receiver: receives mipi data from a MIPI camera sensor.
+- MIPI CSIRx Controller: is responsible for handling and decoding CSI2 protocol
+  based camera sensor data stream.
+- ISP: handles the image data streams from the MIPI CSIRx Controller.
+- VIN(Video In): a top-level module, is responsible for controlling power
+  and clocks to other modules, dumps the input data to memory or transfers the
+  input data to ISP.
+
+
+Topology
+--------
+
+The media controller pipeline graph is as follows:
+
+.. _starfive_camss_graph:
+
+.. kernel-figure:: starfive_camss_graph.dot
+    :alt:   starfive_camss_graph.dot
+    :align: center
+
+The driver has 5 video devices:
+
+- stf_vin0_wr_video0: capture device for images directly from the VIN module.
+- stf_vin0_isp0_video1: capture device for images without scaling.
+- stf_vin0_isp0_ss0_video2: capture device for images with adjustable
+  scale-down factor.
+- stf_vin0_isp0_ss1_video3: capture device for images with adjustable
+  scale-down factor.
+- stf_vin0_isp0_raw_video4: capture device for RAW images.
+
+The driver has 6 subdevices:
+
+- stf_isp0: is responsible for all the isp operations.
+- stf_vin0_wr: used to dump RAW images to memory.
+- stf_vin0_isp0: used to capture unscaled images for the stf_vin0_isp0_video1
+  device.
+- stf_vin0_isp0_ss0: used to resize and downsample frames for
+  the stf_vin0_isp0_ss0_video2 capture device.
+- stf_vin0_isp0_ss1: used to resize and downsample frames for
+  the stf_vin0_isp0_ss1_video3 capture device.
+- stf_vin0_isp0_raw: used to configure the camss ISP to get RAW
+  images for stf_vin0_isp0_raw_video4 capture device.
diff --git a/Documentation/admin-guide/media/starfive_camss_graph.dot b/Documentation/admin-guide/media/starfive_camss_graph.dot
new file mode 100644
index 000000000000..c35dec8de254
--- /dev/null
+++ b/Documentation/admin-guide/media/starfive_camss_graph.dot
@@ -0,0 +1,28 @@
+digraph board {
+	rankdir=TB
+	n00000001 [label="{{<port0> 0} | stf_isp0\n/dev/v4l-subdev0 | {<port1> 1 | <port2> 2 | <port3> 3 | <port4> 4}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000001:port1 -> n00000010:port0
+	n00000001:port2 -> n00000019:port0 [style=dashed]
+	n00000001:port3 -> n00000022:port0 [style=dashed]
+	n00000001:port4 -> n0000002b:port0 [style=dashed]
+	n00000007 [label="{{<port0> 0} | stf_vin0_wr\n/dev/v4l-subdev1 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000007:port1 -> n0000000a [style=bold]
+	n0000000a [label="stf_vin0_wr_video0\n/dev/video0", shape=box, style=filled, fillcolor=yellow]
+	n00000010 [label="{{<port0> 0} | stf_vin0_isp0\n/dev/v4l-subdev2 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000010:port1 -> n00000013 [style=bold]
+	n00000013 [label="stf_vin0_isp0_video1\n/dev/video1", shape=box, style=filled, fillcolor=yellow]
+	n00000019 [label="{{<port0> 0} | stf_vin0_isp0_ss0\n/dev/v4l-subdev3 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000019:port1 -> n0000001c [style=bold]
+	n0000001c [label="stf_vin0_isp0_ss0_video2\n/dev/video2", shape=box, style=filled, fillcolor=yellow]
+	n00000022 [label="{{<port0> 0} | stf_vin0_isp0_ss1\n/dev/v4l-subdev4 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000022:port1 -> n00000025 [style=bold]
+	n00000025 [label="stf_vin0_isp0_ss1_video3\n/dev/video3", shape=box, style=filled, fillcolor=yellow]
+	n0000002b [label="{{<port0> 0} | stf_vin0_isp0_raw\n/dev/v4l-subdev5 | {<port1> 1}}", shape=Mrecord, style=filled, fillcolor=green]
+	n0000002b:port1 -> n0000002e [style=bold]
+	n0000002e [label="stf_vin0_isp0_raw_video4\n/dev/video4", shape=box, style=filled, fillcolor=yellow]
+	n0000003c [label="{{<port0> 0} | cdns_csi2rx.19800000.csi-bridge\n/dev/v4l-subdev6 | {<port1> 1 | <port2> 2 | <port3> 3 | <port4> 4}}", shape=Mrecord, style=filled, fillcolor=green]
+	n0000003c:port1 -> n00000007:port0 [style=dashed]
+	n0000003c:port1 -> n00000001:port0
+	n00000054 [label="{{} | imx219 6-0010\n/dev/v4l-subdev7 | {<port0> 0}}", shape=Mrecord, style=filled, fillcolor=green]
+	n00000054:port0 -> n0000003c:port0 [style=bold]
+}
diff --git a/Documentation/admin-guide/media/v4l-drivers.rst b/Documentation/admin-guide/media/v4l-drivers.rst
index 90a026ee05c6..186f8b0a082d 100644
--- a/Documentation/admin-guide/media/v4l-drivers.rst
+++ b/Documentation/admin-guide/media/v4l-drivers.rst
@@ -30,6 +30,7 @@ Video4Linux (V4L) driver-specific documentation
 	si470x
 	si4713
 	si476x
+	starfive
 	vimc
 	visl
 	vivid
-- 
2.34.1