Documentation/userspace-api/media/v4l/metafmt-arm-mali-c55.rst

Source file repositories/reference/linux-study-clean/Documentation/userspace-api/media/v4l/metafmt-arm-mali-c55.rst

File Facts

System
Linux kernel
Corpus path
Documentation/userspace-api/media/v4l/metafmt-arm-mali-c55.rst
Extension
.rst
Size
3064 bytes
Lines
85
Domain
Support Tooling And Documentation
Bucket
Documentation
Inferred role
Support Tooling And Documentation: documentation
Status
atlas-only

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

.. SPDX-License-Identifier: GPL-2.0

.. _v4l2-meta-fmt-mali-c55-params:
.. _v4l2-meta-fmt-mali-c55-stats:

*****************************************************************************
V4L2_META_FMT_MALI_C55_STATS ('C55S'), V4L2_META_FMT_MALI_C55_PARAMS ('C55P')
*****************************************************************************

3A Statistics
=============

The ISP device collects different statistics over an input bayer frame. Those
statistics can be obtained by userspace from the
:ref:`mali-c55 3a stats <mali-c55-3a-stats>` metadata capture video node, using
the :c:type:`v4l2_meta_format` interface. The buffer contains a single instance
of the C structure :c:type:`mali_c55_stats_buffer` defined in
``mali-c55-config.h``, so the structure can be obtained from the buffer by:

.. code-block:: C

	struct mali_c55_stats_buffer *stats =
		(struct mali_c55_stats_buffer *)buf;

For details of the statistics see :c:type:`mali_c55_stats_buffer`.

Configuration Parameters
========================

The configuration parameters are passed to the :ref:`mali-c55 3a params
<mali-c55-3a-params>` 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 for the Mali-C55
use the 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:`mali_c55_param_block_type`.

.. 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 mali_c55_params_awb_gains *gains =
		(struct mali_c55_params_awb_gains *)data;

	gains->header.type = MALI_C55_PARAM_BLOCK_AWB_GAINS;
	gains->header.flags |= V4L2_ISP_PARAMS_FL_BLOCK_ENABLE;
	gains->header.size = sizeof(struct mali_c55_params_awb_gains);

	gains->gain00 = 256;
	gains->gain00 = 256;
	gains->gain00 = 256;
	gains->gain00 = 256;

	data += sizeof(struct mali_c55_params_awb_gains);
	params->data_size += sizeof(struct mali_c55_params_awb_gains);

	struct mali_c55_params_sensor_off_preshading *blc =
		(struct mali_c55_params_sensor_off_preshading *)data;

	blc->header.type = MALI_C55_PARAM_BLOCK_SENSOR_OFFS;

Annotation

Implementation Notes