[0/7] Raspberry Pi AEC/AGC update
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Message ID 20250617082956.5699-1-david.plowman@raspberrypi.com
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  • Raspberry Pi AEC/AGC update
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David Plowman June 17, 2025, 8:29 a.m. UTC 
Hi everyone

Here's a patch set that originated way back at the end of 2023! I
remember thinking "oh, I'll send these patches once Pi 5 support has
been merged", thinking it would only be a few weeks. How young and
foolish I was!

Anyway, it was so long ago now, that I felt rather like I was
reviewing a patch set from another person - "past David", I suppose.

The first 3 patches are small technical or cosmetic improvements, not
of any particularly great consequence. Each is standalone. I think I'm
happy that past David seemed to know what he was doing.

The remaining 4 patches are the important ones. Our AEC/AGC has always
had a problem because the digital gain was set in its prepare()
method.  The catch is that if we're running at high framerates, we
frequently skip the IPAs altogether, meaning the digital gain that is
required - because it's making up for a deficit in exposure - doesn't
get applied. This causes some sometimes very obvious "winks".

In these 4 last patches, calculation of the digital gain is moved out
of prepare() to process(), meaning it's always available. And the IPA
code is refactored slightly so that the digital gain is always
applied, even when the rest of AEC/AGC is skipped.

I hope it makes reasonable sense - there is some fiddly stuff going on
here. Hats off to past David!

Thanks!

Present-day David


David Plowman (7):
  ipa: rpi: agc: Change handling of colour gains less than 1
  ipa: rpi: agc: Make the maximum digital gain configurable
  ipa: rpi: agc: Rename "analogue gain" to "gain" where appropriate
  ipa: rpi: Advance the delay context counter even when IPAs don't run
  ipa: rpi: agc: Calculate digital gain in process()
  ipa: rpi: Update digital gain handling in IPA base and derived classes
  ipa: rpi: agc: Remove digital gain from AgcPrepareStatus

 src/ipa/rpi/common/ipa_base.cpp            |  72 ++++---
 src/ipa/rpi/common/ipa_base.h              |   6 +-
 src/ipa/rpi/controller/agc_algorithm.h     |   2 +-
 src/ipa/rpi/controller/agc_status.h        |   4 +-
 src/ipa/rpi/controller/rpi/agc.cpp         |   6 +-
 src/ipa/rpi/controller/rpi/agc.h           |   4 +-
 src/ipa/rpi/controller/rpi/agc_channel.cpp | 236 +++++++++------------
 src/ipa/rpi/controller/rpi/agc_channel.h   |   6 +-
 src/ipa/rpi/pisp/pisp.cpp                  |  81 ++++---
 src/ipa/rpi/vc4/vc4.cpp                    |  42 +++-
 10 files changed, 248 insertions(+), 211 deletions(-)