[PATCH v2 14/15] docs: admin-guide: media: bcm2835-isp: Add documentation for bcm2835-isp

Umang Jain
2023-11-09T21:04:53Z

From: Naushir Patuck <naush@raspberrypi.com>

Document device nodes, frame buffer formats and initial set of
configuraiton that can be set from userspace to configure the pipeline.

Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
Signed-off-by: Umang Jain <umang.jain@ideasonboard.com>
---
.../admin-guide/media/bcm2835-isp.rst | 127 ++++++++++++++++++
.../userspace-api/media/drivers/index.rst | 1 +
2 files changed, 128 insertions(+)
create mode 100644 Documentation/admin-guide/media/bcm2835-isp.rst

diff --git a/Documentation/admin-guide/media/bcm2835-isp.rst b/Documentation/admin-guide/media/bcm2835-isp.rst
new file mode 100644
index 000000000000..e1c19f78435e
--- /dev/null
+++ b/Documentation/admin-guide/media/bcm2835-isp.rst
@@ -0,0 +1,127 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+BCM2835 ISP Driver
+==================
+
+Introduction
+------------
+
+The BCM2835 Image Sensor Pipeline (ISP) is a fixed function hardware pipeline
+for performing image processing operations. Images are fed to the input
+of the ISP through memory frame buffers. These images may be in various YUV,
+RGB, or Bayer formats. A typical use case would have Bayer images obtained from
+an image sensor by the BCM2835 Unicam peripheral, written to a memory
+frame buffer, and finally fed into the input of the ISP. Two concurrent output
+images may be generated in YUV or RGB format at different resolutions.
+Statistics output is also generated for Bayer input images.
+
+The bcm2835-isp driver exposes the following media pads as V4L2 device nodes:
+
+.. tabularcolumns:: |l|l|l|l|
+
+.. cssclass: longtable
+
+.. flat-table::
+
+ * - *Pad*
+ - *Direction*
+ - *Purpose*
+ - *Formats*
+
+ * - "bcm2835-isp0-output0"
+ - sink
+ - Accepts Bayer, RGB or YUV format frame buffers as input to the ISP HW
+ pipeline.
+ - :ref:`RAW8 <V4L2-PIX-FMT-SRGGB8>`,
+ :ref:`RAW10P <V4L2-PIX-FMT-SRGGB10P>`,
+ :ref:`RAW12P <V4L2-PIX-FMT-SRGGB12P>`,
+ :ref:`RAW14P <V4L2-PIX-FMT-SRGGB14P>`,
+ :ref:`RAW16 <V4L2-PIX-FMT-SRGGB16>`,
+ :ref:`RGB24/BGR24 <V4L2-PIX-FMT-RGB24>`,
+ :ref:`YUYV <V4L2-PIX-FMT-YUYV>`,
+ :ref:`YVYU <V4L2-PIX-FMT-YVYU>`,
+ :ref:`UYVY <V4L2-PIX-FMT-UYVY>`,
+ :ref:`VYUY <V4L2-PIX-FMT-VYUY>`,
+ :ref:`YUV420/YVU420 <V4L2-PIX-FMT-YUV420>`
+
+ * - "bcm2835-isp0-capture1"
+ - source
+ - High resolution YUV or RGB processed output from the ISP.
+ - :ref:`RGB565 <V4L2-PIX-FMT-RGB565>`,
+ :ref:`RGB24/BGR24 <V4L2-PIX-FMT-RGB24>`,
+ :ref:`ABGR32 <V4L2-PIX-FMT-ABGR32>`,
+ :ref:`YUYV <V4L2-PIX-FMT-YUYV>`,
+ :ref:`YVYU <V4L2-PIX-FMT-YVYU>`,
+ :ref:`UYVY <V4L2-PIX-FMT-UYVY>`,
+ :ref:`VYUY <V4L2-PIX-FMT-VYUY>`.
+ :ref:`YUV420/YVU420 <V4L2-PIX-FMT-YUV420>`,
+ :ref:`NV12/NV21 <V4L2-PIX-FMT-NV12>`,
+
+ * - "bcm2835-isp0-capture2"
+ - source
+ - Low resolution YUV processed output from the ISP. The output of
+ this pad cannot have a resolution larger than the "bcm2835-isp0-capture1" pad in any dimension.
+ - :ref:`YUYV <V4L2-PIX-FMT-YUYV>`,
+ :ref:`YVYU <V4L2-PIX-FMT-YVYU>`,
+ :ref:`UYVY <V4L2-PIX-FMT-UYVY>`,
+ :ref:`VYUY <V4L2-PIX-FMT-VYUY>`.
+ :ref:`YUV420/YVU420 <V4L2-PIX-FMT-YUV420>`,
+ :ref:`NV12/NV21 <V4L2-PIX-FMT-NV12>`,
+
+ * - "bcm2835-isp0-capture1"
+ - source
+ - Image statistics calculated from the input image provided on the
+ "bcm2835-isp0-output0" pad. Statistics are only available for Bayer
+ format input images.
+ - :ref:`v4l2-meta-fmt-bcm2835-isp-stats`.
+
+Pipeline Configuration
+----------------------
+
+The ISP pipeline can be configure through user-space by calling
+:ref:`VIDIOC_S_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` on the “bcm2835-isp0-output0”
+node with the appropriate parameters as shown in the table below.
+
+.. tabularcolumns:: |p{2cm}|p{5.0cm}|
+
+.. cssclass: longtable
+
+.. flat-table::
+
+ * - *id*
+ - *Parameter*
+
+ * - ``V4L2_CID_USER_BCM2835_ISP_CC_MATRIX``
+ - struct :c:type:`bcm2835_isp_custom_ccm`
+
+ * - ``V4L2_CID_USER_BCM2835_ISP_LENS_SHADING``
+ - struct :c:type:`bcm2835_isp_lens_shading`
+
+ * - ``V4L2_CID_USER_BCM2835_ISP_BLACK_LEVEL``
+ - struct :c:type:`bcm2835_isp_black_level`
+
+ * - ``V4L2_CID_USER_BCM2835_ISP_GEQ``
+ - struct :c:type:`bcm2835_isp_geq`
+
+ * - ``V4L2_CID_USER_BCM2835_ISP_GAMMA``
+ - struct :c:type:`bcm2835_isp_gamma`
+
+ * - ``V4L2_CID_USER_BCM2835_ISP_DENOISE``
+ - struct :c:type:`bcm2835_isp_denoise`
+
+ * - ``V4L2_CID_USER_BCM2835_ISP_SHARPEN``
+ - struct :c:type:`bcm2835_isp_sharpen`
+
+ * - ``V4L2_CID_USER_BCM2835_ISP_DPC``
+ - struct :c:type:`bcm2835_isp_dpc`
+
+++++++++++++++++++++++++
+Configuration Parameters
+++++++++++++++++++++++++
+
+.. kernel-doc:: include/uapi/linux/bcm2835-isp.h
+ :functions: bcm2835_isp_rational bcm2835_isp_ccm bcm2835_isp_custom_ccm
+ bcm2835_isp_gain_format bcm2835_isp_lens_shading
+ bcm2835_isp_black_level bcm2835_isp_geq bcm2835_isp_gamma
+ bcm2835_isp_denoise bcm2835_isp_sharpen
+ bcm2835_isp_dpc_mode bcm2835_isp_dpc
diff --git a/Documentation/userspace-api/media/drivers/index.rst b/Documentation/userspace-api/media/drivers/index.rst
index 1726f8ec86fa..05e20a4e1d53 100644
--- a/Documentation/userspace-api/media/drivers/index.rst
+++ b/Documentation/userspace-api/media/drivers/index.rst
@@ -33,6 +33,7 @@ For more details see the file COPYING in the source distribution of Linux.

aspeed-video
camera-sensor
+ bcm2835-isp
ccs
cx2341x-uapi
dw100
--
2.41.0