[libcamera-devel] [PATCH 00/10] Raspberry Pi AGC

[David Plowman]

Hi everyone

Some time ago I had said I was doing some maintanence on the Raspberry
Pi AGC algorithm, so here it all is (finally). Some of the changes are
just for tidying, but others do also make it work better (even
correctly). Some of the changes are in particular designed to go with
Naush's patch set that allows exposure/gain to be set before the
camera starts, though they all function in their own right too.

These are the last substantial set of changes I have before we can
publish our libcamera apps, though I think Naush still has more. (I am
doing work on some of the other algorithms, but these are not on the
critical path and can be added later.)

Let me summarise all the individual patches here:

#1. Replace Raspberry Pi debug with libcamera debug.

#2. Code simplification. A number of copies and mutexes are
 unnecessary on the libcamera/vc4 platform. Not really a functional
 change though it does happen to fix a bug (where the AeLocked status
 was never correctly passed out in the AgcStatus).

#3. Function renamed to be clearer!

#4. An improvement in the way average Y values are calculated. This
 does actually change the AGC behaviour, making it less fiercely
 centre-weighted.

#5. Code that fetches the AwbStatus from the metadata is factored out,
 so that we don't keep doing it all over the place. No functional
 difference.

#6. An update to the AWB so that it gives us its up-to-date values
 when a camera mode switch happens. There's actually quite a lot of
 tidying to do to the AWB, but I'd like to save that for when I have
 more substantial changes there (and don't worry, they will come!).

#7. This passes out correct gain/exposure values when the camera
 changes mode (or starts). This is the one most important to Naush.

#8. Clear up some uninitialised variables. This is Tomi's patch from a
 little while back.

#9. A small improvement to the gain update calculation. It's worth
 working a little harder with the statistics that we have to save
 having to wait for more frames.

#10. Improvements to the "AE locked" logic. Previously it could fail
 ever to "lock" in some circumstances; now it will always do so once
 the AGC is steady.

Sorry there's quite such a lot of stuff here. Please let me know if it
might be better broken up into a few smaller patch sets.

Thanks and best regards
David

David Plowman (10):
  libcamera: ipa: raspberrypi: agc: Use libcamera debug
  libcamera: ipa: raspberrypi: agc: Remove unnecessary locking
  libcamera: ipa: raspberrypi: agc: Rename method to divideUpExposure
  libcamera: ipa: raspberrypi: agc: Improve centre-weighted luminance
    calucation
  libcamera: ipa: raspberrypi: agc: Fetch AWB status only once
  libcamera: ipa: raspberrypi: awb: Add SwitchMode method to output AWB
    status
  libcamera: ipa: raspberrypi: agc: Report fixed exposure/gain values
    during SwitchMode
  libcamera: src: ipa: raspberrypi: agc: Fix uninitialised members in
    status_
  libcamera: src: ipa: raspberrypi: agc: Improve gain update calculation
    for partly saturated images
  libcamera: src: ipa: raspberrypi: agc: Improve AE locked logic

 src/ipa/raspberrypi/controller/rpi/agc.cpp | 393 ++++++++++++---------
 src/ipa/raspberrypi/controller/rpi/agc.hpp |  17 +-
 src/ipa/raspberrypi/controller/rpi/awb.cpp |  14 +
 src/ipa/raspberrypi/controller/rpi/awb.hpp |   1 +
 4 files changed, 248 insertions(+), 177 deletions(-)

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2.20.1