[libcamera-devel] [PATCH] android: Make libyaml dependency optional

[Laurent Pinchart]

Hi Roman,

On Tue, Dec 28, 2021 at 01:22:34PM +0200, Roman Stratiienko wrote:
> вт, 28 дек. 2021 г., 13:04 Jacopo Mondi:
> > Hi Roman,
> >
> > cc Hanlin Chen from ChromiumOS as he's planning to extend
> > configuration file support for the ChromeOS Android HAL.
> 
> > Before looking into the patch: is there any hope libyaml might become
> > part of the standard AOSP distribution (or a process in place to request
> > that)
> 
> I am not aware of that, and I haven't initiated such a process. It will be
> a very slow and bumpy road.
> 
> Not sure what is planned for these properties in future, but now it is not
> necessary to have it in libcamera to have fully functional hal. Also having
> no configuration file available will encourage developers to add
> corresponding records to dts, which is also a great thing to align with
> linux world.

Our goals align here. This is exactly why we have decided not to set the
camera location in a configuration file for the libcamera core, but to
isolate it in the HAL as a temporary (but in practice likely a long-term
temporary) measure, as we have to support platforms that will take some
time before a firmware (ACPI in this case) update can be deployed.

This being said, we will introduce a configuration file for the
libcamera core in the near future, and we also plan to use libyaml
there. The tuning files for the IPU3 and RkISP1 IPA modules will also
use YAML, and I'd like to move the Raspberry Pi tuning files from JSON
to YAML for consistency.

We could merge this patch in the meantime, but compilation on Android
will likely break again soon. I wonder if we couldn't instead use a
meson wrap to include libyaml as a subproject. This should solve the
issue in the longer term.

By the way, out of curiosity, how do you compile libcamera for Android ?
We have a look at Soong (as the Makefile-based build system is being
phased out), but blueprint files don't support all our needs (and would
be annoying to maintain manually), and there's no way we found to
generate Android.bp files from meson in a way that would integrate with
Soong. This is still an unsolved problem, and I'm increasingly tempted
to do the same as mesa3d and just document that libcamera should be
built outside of AOSP, using the NDK.

> > On Tue, Dec 28, 2021 at 11:51:53AM +0200, Roman Stratiienko wrote:
> > > Mainline Android has no libyaml in-tree. Moreover camera_hal_config.cpp
> > > uses std::filesystem class that is not permitted for AOSP VNDK vendor
> > > libraries.
> > >
> > > External configuration file is no longer mandatory and DTS overlays can
> > > be used to specify camera location and rotation.
> > >
> > > Do not require external configuration file for cases where meson.build
> > > can't find libyaml. Assume that cameras without location specified
> > > by V4L2 properties are always external.
> > >
> > > Signed-off-by: Roman Stratiienko <roman.o.stratiienko at globallogic.com>
> > > ---
> > >  src/android/camera_hal_manager.cpp | 13 +++++++++++++
> > >  src/android/camera_hal_manager.h   |  2 ++
> > >  src/android/meson.build            | 10 ++++++++--
> > >  3 files changed, 23 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/src/android/camera_hal_manager.cpp b/src/android/camera_hal_manager.cpp
> > > index 5f7bfe265c71b..9e575bfa5204a 100644
> > > --- a/src/android/camera_hal_manager.cpp
> > > +++ b/src/android/camera_hal_manager.cpp
> > > @@ -48,6 +48,7 @@ int CameraHalManager::init()
> > >  {
> > >       cameraManager_ = std::make_unique<CameraManager>();
> > >
> > > +#ifdef HAVE_LIBYAML
> > >       /*
> > >        * If the configuration file is not available the HAL only supports
> > >        * external cameras. If it exists but it's not valid then error out.
> > > @@ -56,6 +57,7 @@ int CameraHalManager::init()
> > >               LOG(HAL, Error) << "HAL configuration file is not valid";
> > >               return -EINVAL;
> > >       }
> > > +#endif
> > >
> > >       /* Support camera hotplug. */
> > >       cameraManager_->cameraAdded.connect(this, &CameraHalManager::cameraAdded);
> > > @@ -133,6 +135,7 @@ void CameraHalManager::cameraAdded(std::shared_ptr<Camera> cam)
> > >               }
> > >       }
> > >
> > > +#ifdef HAVE_LIBYAML
> > >       /*
> > >        * The configuration file must be valid, and contain a corresponding
> > >        * entry for internal cameras. External cameras can be initialized
> > > @@ -145,6 +148,16 @@ void CameraHalManager::cameraAdded(std::shared_ptr<Camera> cam)
> > >       }
> > >
> > >       const CameraConfigData *cameraConfigData = halConfig_.cameraConfigData(cam->id());
> > > +#else
> > > +     /*
> > > +      * Assume that cameras without properties::Location specified are external.
> > > +      */
> > > +     const CameraConfigData *cameraConfigData = nullptr;
> > > +     if (!isCameraExternal && cameraLocation(cam.get()) < 0) {
> > > +             isCameraExternal = true;
> > > +             id = nextExternalCameraId_;
> > > +     }
> > > +#endif
> > >
> > >       /*
> > >        * Some cameras whose location is reported by libcamera as external may
> > > diff --git a/src/android/camera_hal_manager.h b/src/android/camera_hal_manager.h
> > > index a5f8b933a7902..056abbb0d4e54 100644
> > > --- a/src/android/camera_hal_manager.h
> > > +++ b/src/android/camera_hal_manager.h
> > > @@ -56,7 +56,9 @@ private:
> > >       CameraDevice *cameraDeviceFromHalId(unsigned int id) LIBCAMERA_TSA_REQUIRES(mutex_);
> > >
> > >       std::unique_ptr<libcamera::CameraManager> cameraManager_;
> > > +#ifdef HAVE_LIBYAML
> > >       CameraHalConfig halConfig_;
> > > +#endif
> > >
> > >       const camera_module_callbacks_t *callbacks_;
> > >       std::vector<std::unique_ptr<CameraDevice>> cameras_ LIBCAMERA_TSA_GUARDED_BY(mutex_);
> > > diff --git a/src/android/meson.build b/src/android/meson.build
> > > index 75b4bf2070851..1e471c291a1e4 100644
> > > --- a/src/android/meson.build
> > > +++ b/src/android/meson.build
> > > @@ -3,7 +3,6 @@
> > >  android_deps = [
> > >      dependency('libexif', required : get_option('android')),
> > >      dependency('libjpeg', required : get_option('android')),
> > > -    dependency('yaml-0.1', required : get_option('android')),
> > >      libcamera_private,
> > >  ]
> > >
> > > @@ -41,7 +40,6 @@ android_hal_sources = files([
> > >      'camera3_hal.cpp',
> > >      'camera_capabilities.cpp',
> > >      'camera_device.cpp',
> > > -    'camera_hal_config.cpp',
> > >      'camera_hal_manager.cpp',
> > >      'camera_metadata.cpp',
> > >      'camera_ops.cpp',
> > > @@ -56,6 +54,14 @@ android_hal_sources = files([
> > >
> > >  android_cpp_args = []
> > >
> > > +libyaml_dep = dependency('yaml-0.1', required : false)
> > > +if libyaml_dep.found()
> > > +    config_h.set('HAVE_LIBYAML', 1)
> > > +    android_hal_sources += files([
> > > +        'camera_hal_config.cpp',
> > > +    ])
> > > +endif
> > > +
> > >  subdir('cros')
> > >  subdir('mm')
> > >

-- 
Regards,

Laurent Pinchart