[libcamera-devel] [PATCH v4 0/7] DelayedControls updates and fixes

[Naushir Patuck]

Hi Laurent,

On Tue, 9 Mar 2021 at 10:33, Laurent Pinchart <
laurent.pinchart at ideasonboard.com> wrote:

> Hi Naush,
>
> On Thu, Mar 04, 2021 at 08:17:21AM +0000, Naushir Patuck wrote:
> > Hi,
> >
> > This version (v4) of the patch series adds two further commits to v3.
> >
> > Patches 1 to 5 are identical to v3, except that I have added a line to
> the commit
> > messages saying the change would break the unit tests because of a
> change in the
> > logic of the helper.
> >
> > Patch 6 updates the unit tests with the correct behavior.
> Unfortunately, my
> > attempts to get vimc working on my platform did not end well, so I made
> a local
> > mod to run the tests with a physical camera device. All tests do pass,
> but I
> > would appreciate if somebody else could run this again with the vimc
> device to
> > verify everything is passing.
> >
> > Patch 7 simply fixes a typo in the unit test filename.
>
> Just for my information, I'd like to get a clear understanding of the
> issues that this series fixes. As far as I know, it addresses
> oscillations in the algorithms for Raspberry Pi. Were those oscillations
> introduced by the switch from the StaggeredCtrls implementation to
> DelayedControls but only noticed later, or are there other changes that
> are involved here ?
>

This series addresses the AGC oscillations observed on the Raspberry Pi
using our algorithm.  The key difference between DelayedControls and
StaggeredCtrls is that the former allows us to queue multiple batches of
ctrls,
whereas the latter would only apply the last queued value.  Hence there
is a pair of indexes to track in DelayedControls, vs a single index in
StaggeredCtrl.  Because of this difference, the behavior between the two
was slightly different (e.g. an additional frame needed to queue a control
to the device by DelayedControls, causing a delay mismatch).

This patch aligns the behavior of the two while keeping the new
functionality
of allowing us to queue multiple batches of ctrls.  This effectively fixes
our
AGC oscillations as well.  This change should work equally well for all
other
vendor AGC algorithms, there is nothing specific to Raspberry Pi in these
commits.

Hope that makes things clearer.

Regards,
Naush


>
> > Naushir Patuck (7):
> >   libcamera: delayed_controls: Add notion of priority write
> >   utils: raspberrypi: Add a DelayedControls log parser
> >   libcamera: delayed_controls: Remove unneeded write when starting up
> >   libcamera: delayed_controls: Remove spurious no-op queued controls
> >   libcamera: delayed_controls: Fix off-by-one error in get()
> >   test: delayed_controls: Fixup tests after recent DelayedControls
> >     changes
> >   test: delayed_controls: Rename delayed_contols.cpp to
> >     delayed_controls.cpp
> >
> >  include/libcamera/internal/delayed_controls.h |  13 +-
> >  src/libcamera/delayed_controls.cpp            |  74 ++++++++----
> >  src/libcamera/pipeline/ipu3/ipu3.cpp          |   8 +-
> >  .../pipeline/raspberrypi/raspberrypi.cpp      |  13 +-
> >  src/libcamera/pipeline/rkisp1/rkisp1.cpp      |   8 +-
> >  ...layed_contols.cpp => delayed_controls.cpp} |  51 +++++---
> >  test/meson.build                              |   2 +-
> >  utils/raspberrypi/delayedctrls_parse.py       | 111 ++++++++++++++++++
> >  8 files changed, 219 insertions(+), 61 deletions(-)
> >  rename test/{delayed_contols.cpp => delayed_controls.cpp} (84%)
> >  create mode 100644 utils/raspberrypi/delayedctrls_parse.py
>
> --
> Regards,
>
> Laurent Pinchart
>
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