Documentation/admin-guide/media/qcom_camss.rst

Source file repositories/reference/linux-study-clean/Documentation/admin-guide/media/qcom_camss.rst

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Documentation/admin-guide/media/qcom_camss.rst
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Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

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.. SPDX-License-Identifier: GPL-2.0

.. include:: <isonum.txt>

Qualcomm Camera Subsystem driver
================================

Introduction
------------

This file documents the Qualcomm Camera Subsystem driver located under
drivers/media/platform/qcom/camss.

The current version of the driver supports the Camera Subsystem found on
Qualcomm MSM8916/APQ8016 and MSM8996/APQ8096 processors.

The driver implements V4L2, Media controller and V4L2 subdev interfaces.
Camera sensor using V4L2 subdev interface in the kernel is supported.

The driver is implemented using as a reference the Qualcomm Camera Subsystem
driver for Android as found in Code Linaro [#f1]_ [#f2]_.


Qualcomm Camera Subsystem hardware
----------------------------------

The Camera Subsystem hardware found on 8x16 / 8x96 processors and supported by
the driver consists of:

- 2 / 3 CSIPHY modules. They handle the Physical layer of the CSI2 receivers.
  A separate camera sensor can be connected to each of the CSIPHY module;
- 2 / 4 CSID (CSI Decoder) modules. They handle the Protocol and Application
  layer of the CSI2 receivers. A CSID can decode data stream from any of the
  CSIPHY. Each CSID also contains a TG (Test Generator) block which can generate
  artificial input data for test purposes;
- ISPIF (ISP Interface) module. Handles the routing of the data streams from
  the CSIDs to the inputs of the VFE;
- 1 / 2 VFE (Video Front End) module(s). Contain a pipeline of image processing
  hardware blocks. The VFE has different input interfaces. The PIX (Pixel) input
  interface feeds the input data to the image processing pipeline. The image
  processing pipeline contains also a scale and crop module at the end. Three
  RDI (Raw Dump Interface) input interfaces bypass the image processing
  pipeline. The VFE also contains the AXI bus interface which writes the output
  data to memory.


Supported functionality
-----------------------

The current version of the driver supports:

- Input from camera sensor via CSIPHY;
- Generation of test input data by the TG in CSID;
- RDI interface of VFE

  - Raw dump of the input data to memory.

    Supported formats:

    - YUYV/UYVY/YVYU/VYUY (packed YUV 4:2:2 - V4L2_PIX_FMT_YUYV /
      V4L2_PIX_FMT_UYVY / V4L2_PIX_FMT_YVYU / V4L2_PIX_FMT_VYUY);
    - MIPI RAW8 (8bit Bayer RAW - V4L2_PIX_FMT_SRGGB8 /
      V4L2_PIX_FMT_SGRBG8 / V4L2_PIX_FMT_SGBRG8 / V4L2_PIX_FMT_SBGGR8);
    - MIPI RAW10 (10bit packed Bayer RAW - V4L2_PIX_FMT_SBGGR10P /
      V4L2_PIX_FMT_SGBRG10P / V4L2_PIX_FMT_SGRBG10P / V4L2_PIX_FMT_SRGGB10P /
      V4L2_PIX_FMT_Y10P);
    - MIPI RAW12 (12bit packed Bayer RAW - V4L2_PIX_FMT_SRGGB12P /
      V4L2_PIX_FMT_SGBRG12P / V4L2_PIX_FMT_SGRBG12P / V4L2_PIX_FMT_SRGGB12P).
    - (8x96 only) MIPI RAW14 (14bit packed Bayer RAW - V4L2_PIX_FMT_SRGGB14P /
      V4L2_PIX_FMT_SGBRG14P / V4L2_PIX_FMT_SGRBG14P / V4L2_PIX_FMT_SRGGB14P).

Annotation

Implementation Notes