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;
blc->header.flags |= V4L2_ISP_PARAMS_FL_BLOCK_ENABLE;
blc->header.size = sizeof(struct mali_c55_params_sensor_off_preshading);

blc->chan00 = 51200;
blc->chan01 = 51200;
blc->chan10 = 51200;
blc->chan11 = 51200;

params->data_size += sizeof(struct mali_c55_params_sensor_off_preshading);

Arm Mali-C55 uAPI data types

.. kernel-doc:: include/uapi/linux/media/arm/mali-c55-config.h