[libcamera-devel] [PATCH 2/6] libcamera-platform: Introduce new platform library
Hirokazu Honda
hiroh at chromium.org
Thu Jun 17 07:15:56 CEST 2021
Hi Kieran,
On Thu, Jun 17, 2021 at 11:21 AM Laurent Pinchart <
laurent.pinchart at ideasonboard.com> wrote:
> Hi Kieran,
>
> Thank you for the patch.
>
> On Wed, Jun 16, 2021 at 04:11:48PM +0100, Kieran Bingham wrote:
> > The libcamera-platform.so will feature internal support functionality
> > that is utilised by libcamera, and can be shared in other places.
>
> I'm sure we'll bikeshed the "platform" name :-) We had mentioned
> "support" previously I believe, and I thought that's what you would use,
> but "platform" doesn't sound too bad. The only downside I can see is
> that it could be construed as a library aimed at abstracting differences
> between platforms. "base" may be another option, although I'm not sure
> to like it (the name comes from Chromium, where it has a similar role as
> the library you're creating here).
>
> > However - the libcamera-platform library does not constitute a part
> > of the public libcamera API directly. It is a layer beneath libcamera
> > which provides common abstractions to internal objects.
>
> That's partly true only I'm afraid, looking at patch 4/6,
> bound_method.h, object.h and signal.h are moved to this library, and
> they're part of the libcamera public API. It's not a problem in itself.
>
> > Signed-off-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
> > ---
> > Documentation/Doxyfile.in | 4 +++-
> > Documentation/meson.build | 2 ++
> > include/libcamera/meson.build | 1 +
> > include/libcamera/platform/meson.build | 9 ++++++++
> > src/libcamera-platform/meson.build | 29 ++++++++++++++++++++++++++
> > src/libcamera/meson.build | 2 ++
> > src/meson.build | 1 +
> > 7 files changed, 47 insertions(+), 1 deletion(-)
> > create mode 100644 include/libcamera/platform/meson.build
> > create mode 100644 src/libcamera-platform/meson.build
> >
> > diff --git a/Documentation/Doxyfile.in b/Documentation/Doxyfile.in
> > index 8305f56af7a8..c1b395bf0b83 100644
> > --- a/Documentation/Doxyfile.in
> > +++ b/Documentation/Doxyfile.in
> > @@ -791,8 +791,10 @@ WARN_LOGFILE =
> > INPUT = "@TOP_SRCDIR@/include/libcamera" \
> > "@TOP_SRCDIR@/src/ipa/libipa" \
> > "@TOP_SRCDIR@/src/libcamera" \
> > + "@TOP_SRCDIR@/src/libcamera-platform" \
> > "@TOP_BUILDDIR@/include/libcamera" \
> > - "@TOP_BUILDDIR@/src/libcamera"
> > + "@TOP_BUILDDIR@/src/libcamera" \
> > + "@TOP_BUILDDIR@/src/libcamera-platform"
> >
>
> Drive-by comment, I've been toying with the idea of splitting the
> Doxygen documentation between the public and internal API.
>
> > # This tag can be used to specify the character encoding of the source
> files
> > # that doxygen parses. Internally doxygen uses the UTF-8 encoding.
> Doxygen uses
> > diff --git a/Documentation/meson.build b/Documentation/meson.build
> > index 9ecf4dfcf79f..01b753f07fb6 100644
> > --- a/Documentation/meson.build
> > +++ b/Documentation/meson.build
> > @@ -27,6 +27,8 @@ if doxygen.found() and dot.found()
> > libcamera_ipa_interfaces,
> > libcamera_public_headers,
> > libcamera_sources,
> > + libcamera_platform_headers,
>
> Following up on the comment in the commit message, do we need
> libcamera_platform_internal_headers and
> libcamera_platform_public_headers ? The distinction between the two
> would be different than for libcamera. We currently don't install the
> internal headers, while we'll need to install the "internal platform"
> headers as they can be used by IPA modules. What I'd like to avoid is
> giving an ABI stability guarantee for the whole platform library.
>
> In any case, it's possibly something we can handle later, but as this
> series makes quite a few internal headers public in libcamera-platform,
> I'm a bit worried we will start using them in the public libcamera API.
> Currently there's no risk of doing so by mistake, as the headers are
> clearly marked as internal by their location, and we would immediately
> spot during review an attempt to move an internal header to the public
> directory.
>
> > + libcamera_platform_sources,
> > libipa_headers,
> > libipa_sources,
> > ],
> > diff --git a/include/libcamera/meson.build
> b/include/libcamera/meson.build
> > index 086c958b0a53..2c3bbeb8df36 100644
> > --- a/include/libcamera/meson.build
> > +++ b/include/libcamera/meson.build
> > @@ -25,6 +25,7 @@ include_dir = libcamera_include_dir / 'libcamera'
> >
> > subdir('internal')
> > subdir('ipa')
> > +subdir('platform')
> >
> > install_headers(libcamera_public_headers,
> > subdir : include_dir)
> > diff --git a/include/libcamera/platform/meson.build
> b/include/libcamera/platform/meson.build
> > new file mode 100644
> > index 000000000000..c8e0d0c5ba12
> > --- /dev/null
> > +++ b/include/libcamera/platform/meson.build
> > @@ -0,0 +1,9 @@
> > +# SPDX-License-Identifier: CC0-1.0
> > +
> > +libcamera_platform_include_dir = libcamera_include_dir / 'platform'
> > +
> > +libcamera_platform_headers = files([
> > +])
> > +
> > +install_headers(libcamera_platform_headers,
> > + subdir: libcamera_platform_include_dir)
> > diff --git a/src/libcamera-platform/meson.build
> b/src/libcamera-platform/meson.build
> > new file mode 100644
> > index 000000000000..64d0dfee2731
> > --- /dev/null
> > +++ b/src/libcamera-platform/meson.build
> > @@ -0,0 +1,29 @@
> > +# SPDX-License-Identifier: CC0-1.0
> > +
> > +libcamera_platform_sources = files([
> > +])
> > +
> > +libcamera_platform_deps = [
> > +]
> > +
> > +libcamera_platform_lib = shared_library('libcamera_platform',
>
> $ ls -d /usr/lib64/lib*-[a-zA-Z]* | wc -l
> 664
> $ ls -d /usr/lib64/lib*_[a-zA-Z]* | wc -l
> 619
>
> Nearly a draw :-) I've checked because I would have sworn '-' was way
> more common than '_', but it seems it's a personal preference.
>
> > + [libcamera_platform_sources,
> libcamera_platform_headers],
>
> You're missing one space in the indentation.
>
> > + name_prefix : '',
>
> Any reason why you can't drop this line and use 'camera_platform' as the
> library name ?
>
> > + install : true,
> > + cpp_args : libcamera_cpp_args,
> > + include_directories :
> libcamera_includes,
>
Noob question: I think libcamera-platform can be built stand-alone.
Why is libcamera_include needed; I think code in libcamera-platform doesn't
include headers built as libcamera.so?
-Hiro
> > + dependencies :
> libcamera_platform_deps)
> > +
> > +libcamera_platform = declare_dependency(sources : [
> > + libcamera_platform_headers,
>
> One space missing here too.
>
> > + ],
> > + include_directories :
> libcamera_includes,
> > + link_with :
> libcamera_platform_lib)
>
> Do we actually need this ? Wouldn't it be enough to just link libcamera
> (and the IPA modules) to libcamera_platform_lib ? The reason we have a
> libcamera_dep is because libcamera generates some headers, which needs
> to be done before anything compiling against those headers gets built.
> That's not needed for the platform library (at least not yet :-)).
>
> > +
> > +pkg_mod = import('pkgconfig')
> > +pkg_mod.generate(libraries : libcamera_platform_lib,
> > + version : '1.0',
> > + name : 'libcamera-platform',
>
> One more reason to name the binary libcamera-platform.so ;-)
>
> > + filebase : 'camera-platform',
> > + description : 'Complex Camera Support Library',
>
> This should be updated.
>
> > + subdirs : 'libcamera')
>
> I wonder if we should have a separate pkgconfig file for
> libcamera-platform, or include the library in the libcamera pkgconfig.
> It's an internal split really, and it wouldn't be nice to force
> applications to deal with the libcamera-platform pkgconfig explicitly.
>
> On the other hand, IPA modules will need this. Maybe we should do both,
> and a libcamera-platform.pc for IPA modules, and include
> libcamera-platform.so in the libraries of libcamera.pc ?
>
> > diff --git a/src/libcamera/meson.build b/src/libcamera/meson.build
> > index 54512652272c..6ba59e4006cb 100644
> > --- a/src/libcamera/meson.build
> > +++ b/src/libcamera/meson.build
> > @@ -127,6 +127,7 @@ libcamera_deps = [
> > libgnutls,
> > liblttng,
> > libudev,
> > + libcamera_platform,
> > dependency('threads'),
> > ]
> >
> > @@ -156,6 +157,7 @@ libcamera_dep = declare_dependency(sources : [
> > libcamera_generated_ipa_headers,
> > ],
> > include_directories :
> libcamera_includes,
> > + dependencies: libcamera_platform,
> > link_with : libcamera)
> >
> > subdir('proxy/worker')
> > diff --git a/src/meson.build b/src/meson.build
> > index a4e96ecd728a..70e1a4618a0f 100644
> > --- a/src/meson.build
> > +++ b/src/meson.build
> > @@ -29,6 +29,7 @@ libcamera_cpp_args = []
> > libcamera_objects = []
> >
> > # libcamera must be built first as a dependency to the other components.
> > +subdir('libcamera-platform')
> > subdir('libcamera')
> >
> > subdir('android')
>
> --
> Regards,
>
> Laurent Pinchart
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.libcamera.org/pipermail/libcamera-devel/attachments/20210617/2f2803e7/attachment-0001.htm>
More information about the libcamera-devel
mailing list