[libcamera-devel] [PATCH 2/3] pipeline: ipa: raspberrypi: Correctly report available control limits

[Laurent Pinchart]

Hi Naush,

Thank you for the patch.

On Tue, Jun 21, 2022 at 01:36:09PM +0100, Naushir Patuck via libcamera-devel wrote:
> On Tue, 21 Jun 2022 at 13:15, Kieran Bingham wrote:
> > Quoting Naushir Patuck via libcamera-devel (2022-06-10 13:25:32)
> > > The ipa currently advertises a static ControlInfoMap to specify the available
> > > controls and their limits. Fix this limitation by having the IPA populate a new
> > > ControlInfoMap with updated limits for ExposureTime, AnalogueGain, and
> > > FrameDurationLimits controls based on the current sensor mode. This new
> > > ControlInfoMap is then returned back to the pipeline handler and available to
> > > the application after a successful Camera::Configure() call.

s/Configure/configure/

> > >
> > > Signed-off-by: Naushir Patuck <naush at raspberrypi.com>
> > > ---
> > >  include/libcamera/ipa/raspberrypi.mojom       |  1 +
> > >  src/ipa/raspberrypi/raspberrypi.cpp           | 24 ++++++++++++++++---
> > >  .../pipeline/raspberrypi/raspberrypi.cpp      |  3 +++
> > >  3 files changed, 25 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/include/libcamera/ipa/raspberrypi.mojom b/include/libcamera/ipa/raspberrypi.mojom
> > > index 77f52c282b0f..c0de435b7b33 100644
> > > --- a/include/libcamera/ipa/raspberrypi.mojom
> > > +++ b/include/libcamera/ipa/raspberrypi.mojom
> > > @@ -45,6 +45,7 @@ struct IPAConfig {
> > >
> > >  struct IPAConfigResult {
> >
> > Aha, I see the precedent for "Result" now. so perhaps it's more suitable
> > in the previous patch than I realised.
> >
> > >         float modeSensitivity;
> > > +       libcamera.ControlInfoMap controlInfo;
> > >  };
> > >
> > >  struct StartConfig {
> > > diff --git a/src/ipa/raspberrypi/raspberrypi.cpp b/src/ipa/raspberrypi/raspberrypi.cpp
> > > index 089528f5e126..295f6b735dc0 100644
> > > --- a/src/ipa/raspberrypi/raspberrypi.cpp
> > > +++ b/src/ipa/raspberrypi/raspberrypi.cpp
> > > @@ -74,8 +74,6 @@ constexpr Duration controllerMinFrameDuration = 1.0s / 30.0;
> > >  /* List of controls handled by the Raspberry Pi IPA */
> > >  static const ControlInfoMap::Map ipaControls{
> > >         { &controls::AeEnable, ControlInfo(false, true) },
> > > -       { &controls::ExposureTime, ControlInfo(0, 999999) },
> > > -       { &controls::AnalogueGain, ControlInfo(1.0f, 32.0f) },
> > >         { &controls::AeMeteringMode, ControlInfo(controls::AeMeteringModeValues) },
> > >         { &controls::AeConstraintMode, ControlInfo(controls::AeConstraintModeValues) },
> > >         { &controls::AeExposureMode, ControlInfo(controls::AeExposureModeValues) },
> > > @@ -89,7 +87,6 @@ static const ControlInfoMap::Map ipaControls{
> > >         { &controls::Sharpness, ControlInfo(0.0f, 16.0f, 1.0f) },
> > >         { &controls::ColourCorrectionMatrix, ControlInfo(-16.0f, 16.0f) },
> > >         { &controls::ScalerCrop, ControlInfo(Rectangle{}, Rectangle(65535, 65535, 65535, 65535), Rectangle{}) },
> > > -       { &controls::FrameDurationLimits, ControlInfo(INT64_C(1000), INT64_C(1000000000)) },
> > >         { &controls::draft::NoiseReductionMode, ControlInfo(controls::draft::NoiseReductionModeValues) }
> > >  };
> > >
> > > @@ -446,6 +443,27 @@ int IPARPi::configure(const IPACameraSensorInfo &sensorInfo,
> > >         ASSERT(controls);
> > >         *controls = std::move(ctrls);
> > >
> > > +       /*
> > > +        * Apply the correct limits to the exposure, gain and frame duration controls
> > > +        * based on the current sensor mode.
> > > +        */
> > > +       ControlInfoMap::Map ctrlMap = ipaControls;
> > > +       const Duration minSensorFrameDuration = mode_.min_frame_length * mode_.line_length;
> > > +       const Duration maxSensorFrameDuration = mode_.max_frame_length * mode_.line_length;
> > > +       ctrlMap.emplace(&controls::FrameDurationLimits,
> > > +  ControlInfo(static_cast<int64_t>(minSensorFrameDuration.get<std::micro>()),
> > > +  static_cast<int64_t>(maxSensorFrameDuration.get<std::micro>())));
> > > +
> > > +       ctrlMap.emplace(&controls::AnalogueGain,
> > > +                       ControlInfo(1.0f, static_cast<float>(helper_->Gain(maxSensorGainCode_))));
> > > +
> > > +       const uint32_t exposureMin = sensorCtrls_.at(V4L2_CID_EXPOSURE).min().get<int32_t>();
> > > +       const uint32_t exposureMax = sensorCtrls_.at(V4L2_CID_EXPOSURE).max().get<int32_t>();
> > > +       ctrlMap.emplace(&controls::ExposureTime,
> > > +  ControlInfo(static_cast<int32_t>(helper_->Exposure(exposureMin).get<std::micro>()),
> > > +  static_cast<int32_t>(helper_->Exposure(exposureMax).get<std::micro>())));
> > > +
> > > +       result->controlInfo = ControlInfoMap(std::move(ctrlMap), controls::controls);
> >
> > aha, this means applications can't read the exposure time / gain
> > controls before the camera is configured.
> >
> > I think that sounds 'correct' - but I wonder if we need to make that
> > clear in some documentation somewhere, or somehow in an extension of
> > 'simple-cam' showing how to manage camera controls. (Not to block this
> > patch of course).
> 
> I did stop to think what to do here.  We could add ControlInfo for
> ExposureTime and AnalogueGain for the "default" sensor mode, but
> getting to the sensor mode is a bit more difficult in ipa::init() as things
> stand.  Additionally, these values would likely have to be ignored by
> the application.  It has to do a camera::Configure() call before starting,
> so the values might have changed, rendering the previous values as
> invalid.
> 
> > We should make sure applications realise they have to recheck controls
> > after a configuration operation. (Maybe that's obvious .. I'm not sure).
> 
> Documenting this is probably a good thing so as to avoid application writers
> from tripping up!

This API is way too fragile, even with documentation. That's fine, we'll
fix it later, but for now I'd like to report *something* even before the
first configure() call. Let's make it as meaningful as reasonable
possible, that will be good enough.

> > I was dwelling on if we should only send the updates to the
> > ControlInfoMap over the IPC mechanism, but I don't think this is
> > critical path, and it's simpler to send the whole updated map - so:
> >
> > Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
> >
> > >         return 0;
> > >  }
> > >
> > > diff --git a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> > > index d980c1a71dd8..4596f2babcea 100644
> > > --- a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> > > +++ b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> > > @@ -940,6 +940,9 @@ int PipelineHandlerRPi::configure(Camera *camera, CameraConfiguration *config)
> > >         /* Store the mode sensitivity for the application. */
> > >         data->properties_.set(properties::SensorSensitivity, result.modeSensitivity);
> > >
> > > +       /* Update the controls that the Raspberry Pi IPA can handle. */
> > > +       data->controlInfo_ = result.controlInfo;
> > > +
> > >         /* Setup the Video Mux/Bridge entities. */
> > >         for (auto &[device, link] : data->bridgeDevices_) {
> > >                 /*

-- 
Regards,

Laurent Pinchart