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

[David Plowman]

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...

Thanks!

David


On Wed, 24 Mar 2021 at 11:44, David Plowman
<david.plowman at raspberrypi.com> 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(-)
>
> --
> 2.20.1
>