[PATCH v2] libcamera: libipa: camera_sensor: Add onsemi AR0144 sensor properties

[Laurent Pinchart]

Hi Kieran,

On Tue, Jul 23, 2024 at 04:41:31PM +0100, Kieran Bingham wrote:
> Quoting Laurent Pinchart (2024-07-04 00:11:36)
> > Provide the onsemi AR0144 camera sensor properties and registration with
> > libipa for the gain code helpers.
> > 
> > Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> > ---
> > Now that the kernel driver has been posted to the linux-media mailing
> > list ([1]), it's time for a second version of this patch.
> > 
> > [1] https://lore.kernel.org/r/20240603230301.26550-1-laurent.pinchart@ideasonboard.com
> > 
> > Changes since RFC:
> > 
> > - Add default case
> > - Add black level
> > ---
> >  src/ipa/libipa/camera_sensor_helper.cpp       | 94 +++++++++++++++++++
> >  .../sensor/camera_sensor_properties.cpp       |  9 ++
> >  2 files changed, 103 insertions(+)
> 
> I think I'll be able to test this soon. Might as well be in by then ;-)
> 
> Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>

The driver hasn't been merged upstream, but is on its way. I've sent an
initial patch series and will continue working on it. Can I merge this
patch already, or should I hold on ?

> > diff --git a/src/ipa/libipa/camera_sensor_helper.cpp b/src/ipa/libipa/camera_sensor_helper.cpp
> > index a1339c83c4cb..1cae0b3840af 100644
> > --- a/src/ipa/libipa/camera_sensor_helper.cpp
> > +++ b/src/ipa/libipa/camera_sensor_helper.cpp
> > @@ -8,6 +8,7 @@
> >  #include "camera_sensor_helper.h"
> >  
> >  #include <cmath>
> > +#include <limits>
> >  
> >  #include <libcamera/base/log.h>
> >  
> > @@ -398,6 +399,99 @@ static constexpr double expGainDb(double step)
> >         return log2_10 * step / 20;
> >  }
> >  
> > +class CameraSensorHelperAr0144 : public CameraSensorHelper
> > +{
> > +public:
> > +       CameraSensorHelperAr0144()
> > +       {
> > +               /* Power-on default value: 168 at 12bits. */
> > +               blackLevel_ = 2688;
> > +       }
> > +
> > +       uint32_t gainCode(double gain) const override
> > +       {
> > +               /* The recommended minimum gain is 1.6842 to avoid artifacts. */
> > +               gain = std::clamp(gain, 1.0 / (1.0 - 13.0 / 32.0), 18.45);
> > +
> > +               /*
> > +                * The analogue gain is made of a coarse exponential gain in
> > +                * the range [2^0, 2^4] and a fine inversely linear gain in the
> > +                * range [1.0, 2.0[. There is an additional fixed 1.153125
> > +                * multiplier when the coarse gain reaches 2^2.
> > +                */
> > +
> > +               if (gain > 4.0)
> > +                       gain /= 1.153125;
> > +
> > +               unsigned int coarse = std::log2(gain);
> > +               unsigned int fine = (1 - (1 << coarse) / gain) * 32;
> > +
> > +               /* The fine gain rounding depends on the coarse gain. */
> > +               if (coarse == 1 || coarse == 3)
> > +                       fine &= ~1;
> > +               else if (coarse == 4)
> > +                       fine &= ~3;
> > +
> > +               return (coarse << 4) | (fine & 0xf);
> > +       }
> > +
> > +       double gain(uint32_t gainCode) const override
> > +       {
> > +               unsigned int coarse = gainCode >> 4;
> > +               unsigned int fine = gainCode & 0xf;
> > +               unsigned int d1;
> > +               double d2, m;
> > +
> > +               switch (coarse) {
> > +               default:
> > +               case 0:
> > +                       d1 = 1;
> > +                       d2 = 32.0;
> > +                       m = 1.0;
> > +                       break;
> > +               case 1:
> > +                       d1 = 2;
> > +                       d2 = 16.0;
> > +                       m = 1.0;
> > +                       break;
> > +               case 2:
> > +                       d1 = 1;
> > +                       d2 = 32.0;
> > +                       m = 1.153125;
> > +                       break;
> > +               case 3:
> > +                       d1 = 2;
> > +                       d2 = 16.0;
> > +                       m = 1.153125;
> > +                       break;
> > +               case 4:
> > +                       d1 = 4;
> > +                       d2 = 8.0;
> > +                       m = 1.153125;
> > +                       break;
> > +               }
> > +
> > +               /*
> > +                * With infinite precision, the calculated gain would be exact,
> > +                * and the reverse conversion with gainCode() would produce the
> > +                * same gain code. In the real world, rounding errors may cause
> > +                * the calculated gain to be lower by an amount negligible for
> > +                * all purposes, except for the reverse conversion. Converting
> > +                * the gain to a gain code could then return the quantized value
> > +                * just lower than the original gain code. To avoid this, tests
> > +                * showed that adding the machine epsilon to the multiplier m is
> > +                * sufficient.
> > +                */
> > +               m += std::numeric_limits<decltype(m)>::epsilon();
> > +
> > +               return m * (1 << coarse) / (1.0 - (fine / d1) / d2);
> > +       }
> > +
> > +private:
> > +       static constexpr double kStep_ = 16;
> > +};
> > +REGISTER_CAMERA_SENSOR_HELPER("ar0144", CameraSensorHelperAr0144)
> > +
> >  class CameraSensorHelperAr0521 : public CameraSensorHelper
> >  {
> >  public:
> > diff --git a/src/libcamera/sensor/camera_sensor_properties.cpp b/src/libcamera/sensor/camera_sensor_properties.cpp
> > index b18524d85b37..4e5217ab51ef 100644
> > --- a/src/libcamera/sensor/camera_sensor_properties.cpp
> > +++ b/src/libcamera/sensor/camera_sensor_properties.cpp
> > @@ -52,6 +52,15 @@ LOG_DEFINE_CATEGORY(CameraSensorProperties)
> >  const CameraSensorProperties *CameraSensorProperties::get(const std::string &sensor)
> >  {
> >         static const std::map<std::string, const CameraSensorProperties> sensorProps = {
> > +               { "ar0144", {
> > +                       .unitCellSize = { 3000, 3000 },
> > +                       .testPatternModes = {
> > +                               { controls::draft::TestPatternModeOff, 0 },
> > +                               { controls::draft::TestPatternModeSolidColor, 1 },
> > +                               { controls::draft::TestPatternModeColorBars, 2 },
> > +                               { controls::draft::TestPatternModeColorBarsFadeToGray, 3 },
> > +                       },
> > +               } },
> >                 { "ar0521", {
> >                         .unitCellSize = { 2200, 2200 },
> >                         .testPatternModes = {
> > 
> > base-commit: 196abb8d1d6e0fe9d190315e72a85eb12d16a554

-- 
Regards,

Laurent Pinchart