[RFC,v3,00/19] ipa: libipa: agc: Take exposure margin into account

28507 mbox series

The maximum available exposure depends on the frame duration, but this
is not considered by the current agc implementation, it fixes the maximum
exposure time based on whatever configuration was used to configure the
algorithm. This means that in certain situations the full exposure range
might not be used, even in dark scenes.

This a third attempt at adapting https://patchwork.libcamera.org/project/libcamera/list/?series=5590
on the current master branch. But now that the agc handling is largely unified,
fewer changes are needed to make this work on every platform.

So effectively only patch 7 is taken directly, but only the exposure margin
introduction part of it.

This was mainly tested on rkisp1+imx219, softisp+ov2740, rppx1+imx708.

Unfortunately, back to RFC this time, mainly due to https://gitlab.freedesktop.org/camera/libcamera/-/work_items/362
It turns out to be a bit problematic. So this version adds significant changes:

  * last exposure stage constitutes a hard-limit for both exposure time and gain,
    this matches the behaviour of the raspberry pi ipa (see AgcChannel::computeTargetExposure() )
    ( https://gitlab.freedesktop.org/camera/libcamera/-/work_items/362 )

  * empty stage list is no longer supported, instead two new exposure modes are introduced:
    minimize and maximize, which implement the very simple behaviour of either minimizing
    or maximizing the exposure time, respectively; these modes are always available,
    even without any specific tuning, and this effectively preserves the current behaviour

  * the default max frame duration is now determined based on the largest
    exposure time among all stages (if any), otherwise it is capped to
    the arbitrary limit of 100ms ~ 10fps

changes in v2:
  * report `FrameDurationLimits` in metadata
  * add exposure margin to more sensor helpers

v2: https://patchwork.libcamera.org/cover/28367/
v1: https://patchwork.libcamera.org/cover/28111/

Barnabás Pőcze (18):
  ipa: libipa: exposure_mode_helper: Remove defaulted destructor
  ipa: libipa: exposure_mode_helper: Keep stage params together
  ipa: libipa: exposure_mode_helper: Remove limit getters
  ipa: libipa: exposure_mode_helper: Move `stageGain` variable
  ipa: libipa: exposure_mode_helper: Handle no stages
  ipa: libipa: exposure_mode_helper: Consider last stage as hard-limit
  ipa: libipa: exposure_mode_helper: Add separate maximize/minimize
    modes
  libcamera: controls: Add two new exposure modes
  ipa: libipa: agc: Keep frame duration limits ordered
  ipa: libipa: agc: Retrieve `FrameDurationLimits` earlier
  ipa: libipa: agc: Report `FrameDurationLimits`
  ipa: libipa: agc: Calculate vblank and frame duration sooner
  ipa: libipa: agc: Take parameters from active state for calculation
  libcamera: pipeline: Set vblank on more platforms
  ipa: libipa: agc: Rework frame duration limit calculation
  ipa: libipa: agc: Move control info map setup
  ipa: libipa: exposure_mode_helper: Add getter for max exp time
  ipa: libipa: agc: Take exposure margin into account

Jacopo Mondi (1):
  ipa: camera_sensor_helper: Introduce exposure margin

 src/ipa/ipu3/algorithms/agc.cpp              |   2 +-
 src/ipa/ipu3/ipu3.cpp                        |   3 +-
 src/ipa/libipa/agc.cpp                       | 311 +++++++++++--------
 src/ipa/libipa/agc.h                         |  18 +-
 src/ipa/libipa/agc_mean_luminance.cpp        |  37 ++-
 src/ipa/libipa/camera_sensor_helper.cpp      |  68 ++++
 src/ipa/libipa/camera_sensor_helper.h        |   2 +
 src/ipa/libipa/exposure_mode_helper.cpp      | 231 +++++++++-----
 src/ipa/libipa/exposure_mode_helper.h        |  50 ++-
 src/ipa/mali-c55/algorithms/agc.cpp          |   2 +-
 src/ipa/mali-c55/mali-c55.cpp                |   3 +-
 src/ipa/rkisp1/algorithms/agc.cpp            |   2 +-
 src/ipa/rkisp1/rkisp1.cpp                    |   4 +-
 src/ipa/softisp/algorithms/agc.cpp           |   2 +-
 src/ipa/softisp/softisp.cpp                  |   3 +-
 src/libcamera/control_ids_core.yaml          |   6 +
 src/libcamera/pipeline/ipu3/ipu3.cpp         |   1 +
 src/libcamera/pipeline/mali-c55/mali-c55.cpp |   1 +
 src/libcamera/pipeline/simple/simple.cpp     |   1 +
 19 files changed, 500 insertions(+), 247 deletions(-)

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2.56.0