[libcamera-devel] [PATCH v1.1 3/4] ipa: raspberrypi: Add camera helper for Sony IMX296 sensor

[Kieran Bingham]

Quoting Laurent Pinchart (2021-12-21 23:44:48)
> From: Naushir Patuck <naush at raspberrypi.com>
> 
> The Sony IMX296 sensor has an exponential gain model, and adds a fixed
> 14.26µs offset to the exposure time expressed in line units.
> 
> Signed-off-by: Naushir Patuck <naush at raspberrypi.com>
> Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> Reviewed-by: Naushir Patuck <naush at raspberrypi.com>

Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>

> ---
> Changes since v1:
> 
> - Drop metadata support
> ---
>  src/ipa/raspberrypi/cam_helper_imx296.cpp | 69 +++++++++++++++++++++++
>  src/ipa/raspberrypi/meson.build           |  1 +
>  2 files changed, 70 insertions(+)
>  create mode 100644 src/ipa/raspberrypi/cam_helper_imx296.cpp
> 
> diff --git a/src/ipa/raspberrypi/cam_helper_imx296.cpp b/src/ipa/raspberrypi/cam_helper_imx296.cpp
> new file mode 100644
> index 000000000000..a1a771cb96d5
> --- /dev/null
> +++ b/src/ipa/raspberrypi/cam_helper_imx296.cpp
> @@ -0,0 +1,69 @@
> +/* SPDX-License-Identifier: BSD-2-Clause */
> +/*
> + * Copyright (C) 2020, Raspberry Pi (Trading) Limited
> + *
> + * cam_helper_imx296.cpp - Camera helper for IMX296 sensor
> + */
> +
> +#include <algorithm>
> +#include <cmath>
> +#include <stddef.h>
> +
> +#include "cam_helper.hpp"
> +
> +using namespace RPiController;
> +using libcamera::utils::Duration;
> +using namespace std::literals::chrono_literals;
> +
> +class CamHelperImx296 : public CamHelper
> +{
> +public:
> +       CamHelperImx296();
> +       uint32_t GainCode(double gain) const override;
> +       double Gain(uint32_t gain_code) const override;
> +       uint32_t ExposureLines(Duration exposure) const override;
> +       Duration Exposure(uint32_t exposure_lines) const override;
> +
> +private:
> +       static constexpr uint32_t maxGainCode = 239;
> +       static constexpr Duration timePerLine = 550.0 / 37.125e6 * 1.0s;
> +
> +       /*
> +        * Smallest difference between the frame length and integration time,
> +        * in units of lines.
> +        */
> +       static constexpr int frameIntegrationDiff = 4;
> +};
> +
> +CamHelperImx296::CamHelperImx296()
> +       : CamHelper(nullptr, frameIntegrationDiff)
> +{
> +}
> +
> +uint32_t CamHelperImx296::GainCode(double gain) const
> +{
> +       uint32_t code = 20 * std::log10(gain) * 10;
> +       return std::min(code, maxGainCode);
> +}
> +
> +double CamHelperImx296::Gain(uint32_t gain_code) const
> +{
> +       return std::pow(10.0, gain_code / 200.0);
> +}
> +
> +uint32_t CamHelperImx296::ExposureLines(Duration exposure) const
> +{
> +       return (exposure - 14.26us) / timePerLine;
> +}
> +
> +Duration CamHelperImx296::Exposure(uint32_t exposure_lines) const
> +{
> +       return exposure_lines * timePerLine + 14.26us;
> +}
> +
> +static CamHelper *Create()
> +{
> +       return new CamHelperImx296();
> +}
> +
> +static RegisterCamHelper reg("imx296", &Create);
> diff --git a/src/ipa/raspberrypi/meson.build b/src/ipa/raspberrypi/meson.build
> index 176055f42248..32897e07dad9 100644
> --- a/src/ipa/raspberrypi/meson.build
> +++ b/src/ipa/raspberrypi/meson.build
> @@ -21,6 +21,7 @@ rpi_ipa_sources = files([
>      'cam_helper_ov5647.cpp',
>      'cam_helper_imx219.cpp',
>      'cam_helper_imx290.cpp',
> +    'cam_helper_imx296.cpp',
>      'cam_helper_imx477.cpp',
>      'cam_helper_imx519.cpp',
>      'cam_helper_ov9281.cpp',
> 
> base-commit: 8ff5a8d548eee7c2cb14b355867debdb29e75419
> prerequisite-patch-id: 94059e3f2e08c8ed4c077cd3fbc9ab5f6a43cbe5
> prerequisite-patch-id: c4afb92de814501d8e0b6f9daa967be862351ed8
> -- 
> Regards,
> 
> Laurent Pinchart
>