[libcamera-devel] [PATCH 13/18] ipa: ipu3: Isolate ipa_context documentation

[Kieran Bingham]

Hi JM,

On 30/09/2021 10:55, Jean-Michel Hautbois wrote:
> From: Kieran Bingham <kieran.bingham at ideasonboard.com>
> 
> The IPU3 IPA core is growing with additional documentation. The
> ipa_context documentation is stored here, but it pushes the IPU3
> documentation and implementation further from the head of the file.
> 
> Furthermore, the ipa_context documentation is outside of the ipa::ipu3
> namespace and isn't identified correctly by Doxygen.
> 
> Move the ipa_context to its own compilation object even though there
> isn't any code, but to maintain consistency with our documentation
> model.
> 
> Correctly re-introduce the documentation into the libcamera::ipa::ipu3
> namespace during the move.
> 
> Signed-off-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
> ---
>  src/ipa/ipu3/ipa_context.cpp | 113 +++++++++++++++++++++++++++++++++++
>  src/ipa/ipu3/ipu3.cpp        | 104 --------------------------------
>  src/ipa/ipu3/meson.build     |   1 +
>  3 files changed, 114 insertions(+), 104 deletions(-)
>  create mode 100644 src/ipa/ipu3/ipa_context.cpp
> 
> diff --git a/src/ipa/ipu3/ipa_context.cpp b/src/ipa/ipu3/ipa_context.cpp
> new file mode 100644
> index 00000000..40d79772
> --- /dev/null
> +++ b/src/ipa/ipu3/ipa_context.cpp
> @@ -0,0 +1,113 @@
> +/* SPDX-License-Identifier: LGPL-2.1-or-later */
> +/*
> + * Copyright (C) 2021, Google Inc.
> + *
> + * ipa_context.cpp - IPU3 IPA Context
> + */
> +
> +#include "ipa_context.h"
> +
> +namespace libcamera::ipa::ipu3 {
> +
> +/**
> + * \file ipa_context.h
> + * \brief Context and state information shared between the algorithms
> + */
> +
> +/**
> + * \struct IPASessionConfiguration
> + * \brief Session configuration for the IPA module
> + *
> + * The session configuration contains all IPA configuration parameters that
> + * remain constant during the capture session, from IPA module start to stop.
> + * It is typically set during the configure() operation of the IPA module, but
> + * may also be updated in the start() operation.
> + */
> +
> +/**
> + * \struct IPAFrameContext
> + * \brief Per-frame context for algorithms
> + *
> + * The frame context stores data specific to a single frame processed by the
> + * IPA. Each frame processed by the IPA has a context associated with it,
> + * accessible through the IPAContext structure.
> + *
> + * \todo Detail how to access contexts for a particular frame
> + *
> + * Each of the fields in the frame context belongs to either a specific
> + * algorithm, or to the top-level IPA module. A field may be read by any
> + * algorithm, but should only be written by its owner.
> + */
> +
> +/**
> + * \struct IPAContext
> + * \brief Global IPA context data shared between all algorithms
> + *
> + * \var IPAContext::configuration
> + * \brief The IPA session configuration, immutable during the session
> + *
> + * \var IPAContext::frameContext
> + * \brief The frame context for the frame being processed
> + *
> + * \todo While the frame context is supposed to be per-frame, this
> + * single frame context stores data related to both the current frame
> + * and the previous frames, with fields being updated as the algorithms
> + * are run. This needs to be turned into real per-frame data storage.
> + */
> +
> +/**
> + * \struct IPASessionConfiguration::grid
> + * \brief Grid configuration of the IPA
> + *
> + * \var IPASessionConfiguration::grid::bdsGrid
> + * \brief Bayer Down Scaler grid plane config used by the kernel
> + *
> + * \var IPASessionConfiguration::grid::bdsOutputSize
> + * \brief BDS output size configured by the pipeline handler
> + */
> +
> +/**
> + * \struct IPAFrameContext::agc
> + * \brief Context for the Automatic Gain Control algorithm
> + *
> + * The exposure and gain determined are expected to be applied to the sensor
> + * at the earliest opportunity.
> + *
> + * \var IPAFrameContext::agc::exposure
> + * \brief Exposure time expressed as a number of lines
> + *
> + * \var IPAFrameContext::agc::gain
> + * \brief Analogue gain multiplier
> + *
> + * The gain should be adapted to the sensor specific gain code before applying.
> + */
> +
> +/**
> + * \struct IPAFrameContext::awb
> + * \brief Context for the Automatic White Balance algorithm
> + *
> + * \struct IPAFrameContext::awb::gains
> + * \brief White balance gains
> + *
> + * \var IPAFrameContext::awb::gains::red
> + * \brief White balance gain for R channel
> + *
> + * \var IPAFrameContext::awb::gains::green
> + * \brief White balance gain for G channel
> + *
> + * \var IPAFrameContext::awb::gains::blue
> + * \brief White balance gain for B channel
> + */
> +
> +/**
> + * \struct IPAFrameContext::toneMapping
> + * \brief Context for ToneMapping and Gamma control
> + *

I think this now causes

 * \var IPAFrameContext::toneMapping::gamma
 * \brief Gamma value for the LUT

to be dropped from here, and needs to be added in.



> + * \var IPAFrameContext::toneMapping::gammaCorrection
> + * \brief Per-pixel tone mapping implemented as a LUT
> + *
> + * The LUT structure is defined by the IPU3 kernel interface. See
> + * <linux/intel-ipu3.h> struct ipu3_uapi_gamma_corr_lut for further details.
> + */
> +
> +} /* namespace libcamera::ipa::ipu3 */
> diff --git a/src/ipa/ipu3/ipu3.cpp b/src/ipa/ipu3/ipu3.cpp
> index 9867c993..1b1fc052 100644
> --- a/src/ipa/ipu3/ipu3.cpp
> +++ b/src/ipa/ipu3/ipu3.cpp
> @@ -37,110 +37,6 @@
>  #include "algorithms/tone_mapping.h"
>  #include "libipa/camera_sensor_helper.h"
>  
> -/**
> - * \file ipa_context.h
> - * \brief Context and state information shared between the algorithms
> - */
> -
> -/**
> - * \struct IPASessionConfiguration
> - * \brief Session configuration for the IPA module
> - *
> - * The session configuration contains all IPA configuration parameters that
> - * remain constant during the capture session, from IPA module start to stop.
> - * It is typically set during the configure() operation of the IPA module, but
> - * may also be updated in the start() operation.
> - */
> -
> -/**
> - * \struct IPAFrameContext
> - * \brief Per-frame context for algorithms
> - *
> - * The frame context stores data specific to a single frame processed by the
> - * IPA. Each frame processed by the IPA has a context associated with it,
> - * accessible through the IPAContext structure.
> - *
> - * \todo Detail how to access contexts for a particular frame
> - *
> - * Each of the fields in the frame context belongs to either a specific
> - * algorithm, or to the top-level IPA module. A field may be read by any
> - * algorithm, but should only be written by its owner.
> - */
> -
> -/**
> - * \struct IPAContext
> - * \brief Global IPA context data shared between all algorithms
> - *
> - * \var IPAContext::configuration
> - * \brief The IPA session configuration, immutable during the session
> - *
> - * \var IPAContext::frameContext
> - * \brief The frame context for the frame being processed
> - *
> - * \todo While the frame context is supposed to be per-frame, this
> - * single frame context stores data related to both the current frame
> - * and the previous frames, with fields being updated as the algorithms
> - * are run. This needs to be turned into real per-frame data storage.
> - */
> -
> -/**
> - * \struct IPASessionConfiguration::grid
> - * \brief Grid configuration of the IPA
> - *
> - * \var IPASessionConfiguration::grid::bdsGrid
> - * \brief Bayer Down Scaler grid plane config used by the kernel
> - *
> - * \var IPASessionConfiguration::grid::bdsOutputSize
> - * \brief BDS output size configured by the pipeline handler
> - */
> -
> -/**
> - * \struct IPAFrameContext::agc
> - * \brief Context for the Automatic Gain Control algorithm
> - *
> - * The exposure and gain determined are expected to be applied to the sensor
> - * at the earliest opportunity.
> - *
> - * \var IPAFrameContext::agc::exposure
> - * \brief Exposure time expressed as a number of lines
> - *
> - * \var IPAFrameContext::agc::gain
> - * \brief Analogue gain multiplier
> - *
> - * The gain should be adapted to the sensor specific gain code before applying.
> - */
> -
> -/**
> - * \struct IPAFrameContext::awb
> - * \brief Context for the Automatic White Balance algorithm
> - *
> - * \struct IPAFrameContext::awb::gains
> - * \brief White balance gains
> - *
> - * \var IPAFrameContext::awb::gains::red
> - * \brief White balance gain for R channel
> - *
> - * \var IPAFrameContext::awb::gains::green
> - * \brief White balance gain for G channel
> - *
> - * \var IPAFrameContext::awb::gains::blue
> - * \brief White balance gain for B channel
> - */
> -
> -/**
> - * \struct IPAFrameContext::toneMapping
> - * \brief Context for ToneMapping and Gamma control
> - *
> - * \var IPAFrameContext::toneMapping::gamma
> - * \brief Gamma value for the LUT
> - *
> - * \var IPAFrameContext::toneMapping::gammaCorrection
> - * \brief Per-pixel tone mapping implemented as a LUT
> - *
> - * The LUT structure is defined by the IPU3 kernel interface. See
> - * <linux/intel-ipu3.h> struct ipu3_uapi_gamma_corr_lut for further details.
> - */
> -
>  /* Minimum grid width, expressed as a number of cells */
>  static constexpr uint32_t kMinGridWidth = 16;
>  /* Maximum grid width, expressed as a number of cells */
> diff --git a/src/ipa/ipu3/meson.build b/src/ipa/ipu3/meson.build
> index 39320980..3194111a 100644
> --- a/src/ipa/ipu3/meson.build
> +++ b/src/ipa/ipu3/meson.build
> @@ -5,6 +5,7 @@ subdir('algorithms')
>  ipa_name = 'ipa_ipu3'
>  
>  ipu3_ipa_sources = files([
> +    'ipa_context.cpp',
>      'ipu3.cpp',
>  ])
>  
>