Add documentation for the Qualcomm CAMSS ISP parameters metadata format (V4L2_META_FMT_QCOM_ISP_PARAMS). The format is built on the V4L2 extensible ISP parameters system, with per-block structs defined in the qcom-camss-config.h uAPI header, and is designed to be shared by any CAMSS ISP engine exposing a parameters metadata output video node. The Offline Processing Engine (OPE) ope_params node is the first consumer, with additional engines expected to add their own parameter blocks in the future.
Signed-off-by: Loic Poulain <[email protected]> --- .../userspace-api/media/v4l/meta-formats.rst | 1 + .../userspace-api/media/v4l/metafmt-qcom-isp.rst | 145 +++++++++++++++++++++ MAINTAINERS | 1 + 3 files changed, 147 insertions(+) diff --git a/Documentation/userspace-api/media/v4l/meta-formats.rst b/Documentation/userspace-api/media/v4l/meta-formats.rst index b5455229837e707c24e134438d5e2fd12cb3bf37..25b46af4d9f7faab37000076c530e9aad5b4a076 100644 --- a/Documentation/userspace-api/media/v4l/meta-formats.rst +++ b/Documentation/userspace-api/media/v4l/meta-formats.rst @@ -20,6 +20,7 @@ These formats are used for the :ref:`metadata` interface only. metafmt-intel-ipu3 metafmt-pisp-be metafmt-pisp-fe + metafmt-qcom-isp metafmt-rkisp1 metafmt-rppx1 metafmt-uvc diff --git a/Documentation/userspace-api/media/v4l/metafmt-qcom-isp.rst b/Documentation/userspace-api/media/v4l/metafmt-qcom-isp.rst new file mode 100644 index 0000000000000000000000000000000000000000..da3dd5f3a5899d4c24c80c74b56e3e7b62b3ad50 --- /dev/null +++ b/Documentation/userspace-api/media/v4l/metafmt-qcom-isp.rst @@ -0,0 +1,145 @@ +.. SPDX-License-Identifier: GPL-2.0 +.. c:namespace:: V4L + +.. _v4l2-meta-fmt-qcom-isp-params: + +************************************** +V4L2_META_FMT_QCOM_ISP_PARAMS ('QCIP') +************************************** + +Configuration Parameters +======================== + +The ``V4L2_META_FMT_QCOM_ISP_PARAMS`` format carries image processing +configuration for the ISP engines found in the Qualcomm Camera Subsystem +(CAMSS). It is passed to a metadata output video node using the +:c:type:`v4l2_meta_format` interface. + +Rather than a single struct containing sub-structs for each configurable area +of the ISP, parameters use the :ref:`v4l2-isp` parameters system, through which +groups of parameters are defined as distinct structs or "blocks" which may be +added to the data member of :c:type:`v4l2_isp_params_buffer`. Userspace is +responsible for populating the data member with the blocks that need to be +configured by the driver. Each block-specific struct embeds +:c:type:`v4l2_isp_params_block_header` as its first member and userspace must +populate the type member with a value from :c:type:`camss_params_block_type`. +Populated blocks must be placed consecutively in the data member, and the +combined size of all populated blocks must be set in the data_size member of +:c:type:`v4l2_isp_params_buffer`. + +The set of supported blocks depends on the CAMSS engine consuming the buffer. +Currently the Offline Processing Engine (OPE) is the only engine defining +parameter blocks, exposed through its ``ope_params`` metadata output video +node; additional engines and blocks may be added to this format in the future. + +Blocks whose header does not carry V4L2_ISP_PARAMS_FL_BLOCK_ENABLE leave the +corresponding hardware module bypassed. Blocks omitted from a buffer keep +their previously programmed configuration. + +OPE processing pipeline +======================= + +The OPE is a memory-to-memory engine that reads a Bayer RAW frame from its +``ope_input`` node and writes a YUV frame to its ``ope_disp_output`` node. The +parameter blocks configure fixed-function hardware modules that the frame data +passes through, in the following order: + +.. code-block:: none + + Bayer RAW in RGB domain YUV domain YUV out + (8/10-bit) +------+ +------+ +------+ +------+ +------+ +------+ (NV12/NV16/ + ----------> | WB |-->| DEMO |-->| CC |-->| GLUT |-->|CHROMA|-->| DSC |-----------> + +------+ +------+ +------+ +------+ |ENHAN | +------+ NV24/GREY) + +------+ + +The stages, and the parameter block that configures each one, are: + +.. flat-table:: OPE pipeline stages + :header-rows: 1 + :stub-columns: 0 + + * - Stage + - Module + - Parameter block + - Function + * - WB + - CLC_WB + - :c:type:`camss_params_ope_wb_gain` + - Per-channel white balance gains and black-level / pedestal offsets, + applied to the raw Bayer data. + * - DEMO + - CLC_DEMO + - *(none)* + - Demosaic: reconstructs a full-resolution RGB image from the Bayer + mosaic. Always enabled; not configurable through this format. + * - CC + - CLC_CC + - :c:type:`camss_params_ope_color_correct` + - Color correction matrix applied in the RGB domain. + * - GLUT + - CLC_GLUT + - :c:type:`camss_params_ope_gamma` + - Per-channel gamma correction curves (256-entry LUTs). + * - CHROMA_ENHAN + - CLC_CHROMA_ENHAN + - :c:type:`camss_params_ope_chroma_enhan` + - RGB to YUV color transfer matrix. + * - DSC + - Downscaler + - *(none)* + - Chroma (and, when required, luma) downscaling to produce the requested + YUV subsampling, e.g. YUV 4:4:4 to 4:2:2 (NV16) or 4:2:0 (NV12). + +The input node accepts 8-bit and 10-bit packed Bayer RAW formats (for example +``V4L2_PIX_FMT_SRGGB8`` and ``V4L2_PIX_FMT_SRGGB10P``). The output node +produces semi-planar YUV (``V4L2_PIX_FMT_NV12`` / ``NV21`` / ``NV16`` / +``NV61`` / ``NV24`` / ``NV42``) or luma-only ``V4L2_PIX_FMT_GREY``. Each +configurable stage is bypassed unless its block carries +``V4L2_ISP_PARAMS_FL_BLOCK_ENABLE``. + +The following example populates an OPE parameters buffer with a white balance +and a gamma correction block: + +.. code-block:: c + + struct v4l2_isp_params_buffer *params = + (struct v4l2_isp_params_buffer *)buffer; + + params->version = V4L2_ISP_PARAMS_VERSION_V1; + params->data_size = 0; + + void *data = (void *)params->data; + + struct camss_params_ope_wb_gain *wb = + (struct camss_params_ope_wb_gain *)data; + + wb->header.type = CAMSS_PARAMS_OPE_WB_GAIN; + wb->header.flags |= V4L2_ISP_PARAMS_FL_BLOCK_ENABLE; + wb->header.size = sizeof(struct camss_params_ope_wb_gain); + + /* Unity gain on all three channels (15uQ10, 1024 = 1.0) */ + wb->g_gain = 1024; + wb->b_gain = 1024; + wb->r_gain = 1024; + + data += sizeof(struct camss_params_ope_wb_gain); + params->data_size += sizeof(struct camss_params_ope_wb_gain); + + struct camss_params_ope_gamma *gamma = + (struct camss_params_ope_gamma *)data; + + gamma->header.type = CAMSS_PARAMS_OPE_GAMMA; + gamma->header.flags |= V4L2_ISP_PARAMS_FL_BLOCK_ENABLE; + gamma->header.size = sizeof(struct camss_params_ope_gamma); + + /* Identity curve (pass-through, gamma 1.0) */ + for (unsigned int i = 0; i < CAMSS_OPE_GAMMA_LUT_SIZE; i++) + gamma->glut[i] = gamma->blut[i] = gamma->rlut[i] = 257 * i; + + data += sizeof(struct camss_params_ope_gamma); + params->data_size += sizeof(struct camss_params_ope_gamma); + +Qualcomm CAMSS ISP uAPI data types +================================== + +.. kernel-doc:: include/uapi/linux/qcom-camss-config.h diff --git a/MAINTAINERS b/MAINTAINERS index 3a19da74d00c9dfb48e900df71a86d4686d3ec2c..b5593f814b60fcbcd88f4b4aad25880d19825dc0 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -22363,6 +22363,7 @@ L: [email protected] S: Maintained F: Documentation/admin-guide/media/qcom_camss.rst F: Documentation/devicetree/bindings/media/qcom,*camss* +F: Documentation/userspace-api/media/v4l/metafmt-qcom-isp.rst F: drivers/media/platform/qcom/camss/ QUALCOMM CLOCK DRIVERS -- 2.34.1
