[libcamera-devel] [PATCH 0/2] Raspberry Pi: handle sensors more flexibly

[Laurent Pinchart]

Hi David,

On Wed, Apr 07, 2021 at 10:13:13AM +0100, David Plowman wrote:
> Hi everyone
> 
> I was wondering if I might give this little pair of changes a teeny
> nudge, don't think there's been any feedback as yet...

Easter got a bit in the way, with its overdoses of chocolate (as I get
older I'm strangely more tempted to cook the easter bunny instead). I'll
get back to reviewing your pending series.

> On Wed, 24 Mar 2021 at 11:44, David Plowman wrote:
> >
> > Hi everyone
> >
> > Here are a couple more patches aimed at allowing us to deal more
> > flexibly with "interesting" sensors.
> >
> > The first patch simply makes the CamHelper's exposure-related methods
> > virtual. This gives greater flexibility on how we deal with sensors
> > where different modes have different signal levels. Differences
> > between modes can be accounted for with the gain methods (already
> > virtual), in the exposure (with this change), or via a combination of
> > the two.
> >
> > Note that another solution to this involves fiddling around with the
> > AGC. It would have to know that modes can have different "base signal
> > levels", and account for the difference. I'm still in several minds
> > about whether I want to do this, so this change gives us options in
> > the meantime, and doesn't preclude messing with the AGC later if we
> > wish.
> >
> > The second commit takes the view that if sensors seem to be asking for
> > the red/blue colour gains, then we should tell them. I guess there's a
> > risk that some sensors might seem to want these numbers, but we find
> > that we don't want to tell them. If that happens maybe the CamHelper
> > would have to tell us what to do, but this approach seems reasonable
> > to me at this point.
> >
> > I also apply a fixed 256x multiplier to the colour gains before
> > passing them to the control. I don't think V4L2 docs mandate any
> > particular scale here? Maybe there's an argument for another
> > CamHelper function "ColourGainCode", or something like that.
> >
> > Thoughts and suggestions welcome as always. Thanks!
> >
> > David
> >
> > David Plowman (2):
> >   ipa: raspberrypi: Make CamHelper exposure methods virtual
> >   ipa: raspberrypi: Update sensor's RED/BLUE balance controls when
> >     present
> >
> >  src/ipa/raspberrypi/cam_helper.hpp              |  4 ++--
> >  src/ipa/raspberrypi/raspberrypi.cpp             | 17 ++++++++++++++---
> >  .../pipeline/raspberrypi/raspberrypi.cpp        |  9 +++++++++
> >  3 files changed, 25 insertions(+), 5 deletions(-)
> >

-- 
Regards,

Laurent Pinchart