<div dir="ltr"><div dir="ltr">Hi Kieran,</div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, Jun 17, 2021 at 11:21 AM Laurent Pinchart <<a href="mailto:laurent.pinchart@ideasonboard.com">laurent.pinchart@ideasonboard.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Hi Kieran,<br>
<br>
Thank you for the patch.<br>
<br>
On Wed, Jun 16, 2021 at 04:11:48PM +0100, Kieran Bingham wrote:<br>
> The libcamera-platform.so will feature internal support functionality<br>
> that is utilised by libcamera, and can be shared in other places.<br>
<br>
I'm sure we'll bikeshed the "platform" name :-) We had mentioned<br>
"support" previously I believe, and I thought that's what you would use,<br>
but "platform" doesn't sound too bad. The only downside I can see is<br>
that it could be construed as a library aimed at abstracting differences<br>
between platforms. "base" may be another option, although I'm not sure<br>
to like it (the name comes from Chromium, where it has a similar role as<br>
the library you're creating here).<br>
<br>
> However - the libcamera-platform library does not constitute a part<br>
> of the public libcamera API directly. It is a layer beneath libcamera<br>
> which provides common abstractions to internal objects.<br>
<br>
That's partly true only I'm afraid, looking at patch 4/6,<br>
bound_method.h, object.h and signal.h are moved to this library, and<br>
they're part of the libcamera public API. It's not a problem in itself.<br>
<br>
> Signed-off-by: Kieran Bingham <<a href="mailto:kieran.bingham@ideasonboard.com" target="_blank">kieran.bingham@ideasonboard.com</a>><br>
> ---<br>
> Documentation/Doxyfile.in | 4 +++-<br>
> Documentation/meson.build | 2 ++<br>
> include/libcamera/meson.build | 1 +<br>
> include/libcamera/platform/meson.build | 9 ++++++++<br>
> src/libcamera-platform/meson.build | 29 ++++++++++++++++++++++++++<br>
> src/libcamera/meson.build | 2 ++<br>
> src/meson.build | 1 +<br>
> 7 files changed, 47 insertions(+), 1 deletion(-)<br>
> create mode 100644 include/libcamera/platform/meson.build<br>
> create mode 100644 src/libcamera-platform/meson.build<br>
> <br>
> diff --git a/Documentation/Doxyfile.in b/Documentation/Doxyfile.in<br>
> index 8305f56af7a8..c1b395bf0b83 100644<br>
> --- a/Documentation/Doxyfile.in<br>
> +++ b/Documentation/Doxyfile.in<br>
> @@ -791,8 +791,10 @@ WARN_LOGFILE =<br>
> INPUT = "@TOP_SRCDIR@/include/libcamera" \<br>
> "@TOP_SRCDIR@/src/ipa/libipa" \<br>
> "@TOP_SRCDIR@/src/libcamera" \<br>
> + "@TOP_SRCDIR@/src/libcamera-platform" \<br>
> "@TOP_BUILDDIR@/include/libcamera" \<br>
> - "@TOP_BUILDDIR@/src/libcamera"<br>
> + "@TOP_BUILDDIR@/src/libcamera" \<br>
> + "@TOP_BUILDDIR@/src/libcamera-platform"<br>
> <br>
<br>
Drive-by comment, I've been toying with the idea of splitting the<br>
Doxygen documentation between the public and internal API.<br>
<br>
> # This tag can be used to specify the character encoding of the source files<br>
> # that doxygen parses. Internally doxygen uses the UTF-8 encoding. Doxygen uses<br>
> diff --git a/Documentation/meson.build b/Documentation/meson.build<br>
> index 9ecf4dfcf79f..01b753f07fb6 100644<br>
> --- a/Documentation/meson.build<br>
> +++ b/Documentation/meson.build<br>
> @@ -27,6 +27,8 @@ if doxygen.found() and dot.found()<br>
> libcamera_ipa_interfaces,<br>
> libcamera_public_headers,<br>
> libcamera_sources,<br>
> + libcamera_platform_headers,<br>
<br>
Following up on the comment in the commit message, do we need<br>
libcamera_platform_internal_headers and<br>
libcamera_platform_public_headers ? The distinction between the two<br>
would be different than for libcamera. We currently don't install the<br>
internal headers, while we'll need to install the "internal platform"<br>
headers as they can be used by IPA modules. What I'd like to avoid is<br>
giving an ABI stability guarantee for the whole platform library.<br>
<br>
In any case, it's possibly something we can handle later, but as this<br>
series makes quite a few internal headers public in libcamera-platform,<br>
I'm a bit worried we will start using them in the public libcamera API.<br>
Currently there's no risk of doing so by mistake, as the headers are<br>
clearly marked as internal by their location, and we would immediately<br>
spot during review an attempt to move an internal header to the public<br>
directory.<br>
<br>
> + libcamera_platform_sources,<br>
> libipa_headers,<br>
> libipa_sources,<br>
> ],<br>
> diff --git a/include/libcamera/meson.build b/include/libcamera/meson.build<br>
> index 086c958b0a53..2c3bbeb8df36 100644<br>
> --- a/include/libcamera/meson.build<br>
> +++ b/include/libcamera/meson.build<br>
> @@ -25,6 +25,7 @@ include_dir = libcamera_include_dir / 'libcamera'<br>
> <br>
> subdir('internal')<br>
> subdir('ipa')<br>
> +subdir('platform')<br>
> <br>
> install_headers(libcamera_public_headers,<br>
> subdir : include_dir)<br>
> diff --git a/include/libcamera/platform/meson.build b/include/libcamera/platform/meson.build<br>
> new file mode 100644<br>
> index 000000000000..c8e0d0c5ba12<br>
> --- /dev/null<br>
> +++ b/include/libcamera/platform/meson.build<br>
> @@ -0,0 +1,9 @@<br>
> +# SPDX-License-Identifier: CC0-1.0<br>
> +<br>
> +libcamera_platform_include_dir = libcamera_include_dir / 'platform'<br>
> +<br>
> +libcamera_platform_headers = files([<br>
> +])<br>
> +<br>
> +install_headers(libcamera_platform_headers,<br>
> + subdir: libcamera_platform_include_dir)<br>
> diff --git a/src/libcamera-platform/meson.build b/src/libcamera-platform/meson.build<br>
> new file mode 100644<br>
> index 000000000000..64d0dfee2731<br>
> --- /dev/null<br>
> +++ b/src/libcamera-platform/meson.build<br>
> @@ -0,0 +1,29 @@<br>
> +# SPDX-License-Identifier: CC0-1.0<br>
> +<br>
> +libcamera_platform_sources = files([<br>
> +])<br>
> +<br>
> +libcamera_platform_deps = [<br>
> +]<br>
> +<br>
> +libcamera_platform_lib = shared_library('libcamera_platform',<br>
<br>
$ ls -d /usr/lib64/lib*-[a-zA-Z]* | wc -l<br>
664<br>
$ ls -d /usr/lib64/lib*_[a-zA-Z]* | wc -l<br>
619<br>
<br>
Nearly a draw :-) I've checked because I would have sworn '-' was way<br>
more common than '_', but it seems it's a personal preference.<br>
<br>
> + [libcamera_platform_sources, libcamera_platform_headers],<br>
<br>
You're missing one space in the indentation.<br>
<br>
> + name_prefix : '',<br>
<br>
Any reason why you can't drop this line and use 'camera_platform' as the<br>
library name ?<br>
<br>
> + install : true,<br>
> + cpp_args : libcamera_cpp_args,<br>
> + include_directories : libcamera_includes,<br></blockquote><div><br></div><div>Noob question: I think libcamera-platform can be built stand-alone.</div><div>Why is libcamera_include needed; I think code in libcamera-platform doesn't include headers built as libcamera.so?</div><div><br></div><div>-Hiro</div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
> + dependencies : libcamera_platform_deps)<br>
> +<br>
> +libcamera_platform = declare_dependency(sources : [<br>
> + libcamera_platform_headers,<br>
<br>
One space missing here too.<br>
<br>
> + ],<br>
> + include_directories : libcamera_includes,<br>
> + link_with : libcamera_platform_lib)<br>
<br>
Do we actually need this ? Wouldn't it be enough to just link libcamera<br>
(and the IPA modules) to libcamera_platform_lib ? The reason we have a<br>
libcamera_dep is because libcamera generates some headers, which needs<br>
to be done before anything compiling against those headers gets built.<br>
That's not needed for the platform library (at least not yet :-)).<br>
<br>
> +<br>
> +pkg_mod = import('pkgconfig')<br>
> +pkg_mod.generate(libraries : libcamera_platform_lib,<br>
> + version : '1.0',<br>
> + name : 'libcamera-platform',<br>
<br>
One more reason to name the binary libcamera-platform.so ;-)<br>
<br>
> + filebase : 'camera-platform',<br>
> + description : 'Complex Camera Support Library',<br>
<br>
This should be updated.<br>
<br>
> + subdirs : 'libcamera')<br>
<br>
I wonder if we should have a separate pkgconfig file for<br>
libcamera-platform, or include the library in the libcamera pkgconfig.<br>
It's an internal split really, and it wouldn't be nice to force<br>
applications to deal with the libcamera-platform pkgconfig explicitly.<br>
<br>
On the other hand, IPA modules will need this. Maybe we should do both,<br>
and a libcamera-platform.pc for IPA modules, and include<br>
libcamera-platform.so in the libraries of libcamera.pc ?<br>
<br>
> diff --git a/src/libcamera/meson.build b/src/libcamera/meson.build<br>
> index 54512652272c..6ba59e4006cb 100644<br>
> --- a/src/libcamera/meson.build<br>
> +++ b/src/libcamera/meson.build<br>
> @@ -127,6 +127,7 @@ libcamera_deps = [<br>
> libgnutls,<br>
> liblttng,<br>
> libudev,<br>
> + libcamera_platform,<br>
> dependency('threads'),<br>
> ]<br>
> <br>
> @@ -156,6 +157,7 @@ libcamera_dep = declare_dependency(sources : [<br>
> libcamera_generated_ipa_headers,<br>
> ],<br>
> include_directories : libcamera_includes,<br>
> + dependencies: libcamera_platform,<br>
> link_with : libcamera)<br>
> <br>
> subdir('proxy/worker')<br>
> diff --git a/src/meson.build b/src/meson.build<br>
> index a4e96ecd728a..70e1a4618a0f 100644<br>
> --- a/src/meson.build<br>
> +++ b/src/meson.build<br>
> @@ -29,6 +29,7 @@ libcamera_cpp_args = []<br>
> libcamera_objects = []<br>
> <br>
> # libcamera must be built first as a dependency to the other components.<br>
> +subdir('libcamera-platform')<br>
> subdir('libcamera')<br>
> <br>
> subdir('android')<br>
<br>
-- <br>
Regards,<br>
<br>
Laurent Pinchart<br>
</blockquote></div></div>