Re: [PATCH v7 2/6] media: admin-guide: Add starfive_camss.rst for Starfive Camera Subsystem

Hi Bryan,

Thank you for your comments.

On 2023/7/26 19:26, Bryan O'Donoghue wrote:

On 19/06/2023 12:28, Jack Zhu wrote:

quoted

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

Signed-off-by: Jack Zhu <jack.zhu@starfivetech.com>
---
  .../admin-guide/media/starfive_camss.rst      | 57 +++++++++++++++++++
  .../media/starfive_camss_graph.dot            | 16 ++++++
  .../admin-guide/media/v4l-drivers.rst         |  1 +
  MAINTAINERS                                   |  1 +
  4 files changed, 75 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..a6378849384f
--- /dev/null
+++ b/Documentation/admin-guide/media/starfive_camss.rst

@@ -0,0 +1,57 @@
+.. 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.

Feels like a terribe nit-pick but you have "mipi" and "MIPI" here. I'd be consistent with one - recommend MIPI throughout your documentation.

Okay, I will keep a consistent description.

quoted

+- 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.

Maybe you've done this elsewhere but, it would be worthwhile describing what the ISP does. Debayering ? 3As ? Just raw dumps ?

Ok, I will add more descriptions in the next version.

quoted

+- 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 2 video devices:
+
+- stf_vin0_wr_video0: capture device for images directly from the VIN module.

OK so you can get the raw images.

quoted

+- stf_vin0_isp0_video1: capture device for images without scaling.
+
+The driver has 3 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 images for the stf_vin0_isp0_video1 device.

But what is being output here ? RGB, jpeg, YUV ?
It would be worth adding a few bits of text to describe that so you don't have to dive into code to understand it.

Ok, I will add more descriptions.

---
bod

-- 
Regards,

Jack Zhu