[Buildroot] [PATCH v2 17/24] opencv: rework V4L/libv4l support

From: Yann E. MORIN <yann.morin.1998@free.fr>
To: buildroot@busybox.net
Subject: [Buildroot] [PATCH v2 17/24] opencv: rework V4L/libv4l support
Date: Sun, 4 May 2014 11:32:51 +0200	[thread overview]
Message-ID: <20140504093251.GD3211@free.fr> (raw)
In-Reply-To: <1398208556-4195-18-git-send-email-s.martin49@gmail.com>

Samuel, All,

On 2014-04-23 01:15 +0200, Samuel Martin spake thusly:
> Starting with the 2.4.7 release, for V4L support, OpenCV does not
> requires a libv4l dependency for its V4L support.
> 
> So, it now provides 2 distincts knobs for this: WITH_V4L and a new
> one: WITH_LIBV4L.
> 
> This patch takes advantage of this new knob and libv4l support is
> now automatically enabled if only the libv4l package is enabled.
> 
> In OpenCV, the logic behind this is:
> - using libv4l if available,
> - otherwise, use v4l2 or v4l API from the kernel if available.
> 
> Signed-off-by: Samuel Martin <s.martin49@gmail.com>
> 
> ---
> changes v1 -> v2:
> - rebase
> - extend commit message
> ---
>  package/opencv/Config.in | 11 ++++++-----
>  package/opencv/opencv.mk | 10 +++++++---
>  2 files changed, 13 insertions(+), 8 deletions(-)
> 
> diff --git a/package/opencv/Config.in b/package/opencv/Config.in
> index 129e0aa..0db239e 100644
> --- a/package/opencv/Config.in
> +++ b/package/opencv/Config.in
> @@ -194,14 +194,15 @@ config BR2_PACKAGE_OPENCV_WITH_TIFF
>  
>  config BR2_PACKAGE_OPENCV_WITH_V4L
>  	bool "v4l support"
> -	depends on BR2_LARGEFILE
> -	depends on BR2_TOOLCHAIN_HAS_THREADS
> -	select BR2_PACKAGE_LIBV4L
>  	help
>  	  Enable Video 4 Linux support.
>  
> -comment "v4l support needs a toolchain w/ largefile, threads"
> -	depends on !BR2_LARGEFILE || !BR2_TOOLCHAIN_HAS_THREADS
> +	  If the package libv4l is enabled, its support is automatically enabled.
> +
> +if BR2_PACKAGE_OPENCV_WITH_V4L && !(BR2_LARGEFILE && BR2_TOOLCHAIN_HAS_THREADS)
> +comment "libv4l support will be disabled."
> +comment "libv4l support needs a toolchain w/ largefile, threads"
> +endif

I don't think we want to have such comments. As I said in my previous
review, it is enough (INHO) to just state so in the help entry.

Except under rare circumstances, we do not warn the user that way. The
usual way is to enable support if the needed package is selected, and
to disable the support otherwise.

Regards,
Yann E. MORIN.

>  comment "Install options"
>  
> diff --git a/package/opencv/opencv.mk b/package/opencv/opencv.mk
> index 14a095c..e6de252 100644
> --- a/package/opencv/opencv.mk
> +++ b/package/opencv/opencv.mk
> @@ -214,10 +214,14 @@ OPENCV_CONF_OPT += -DWITH_TIFF=OFF
>  endif
>  
>  ifeq ($(BR2_PACKAGE_OPENCV_WITH_V4L),y)
> -OPENCV_CONF_OPT += -DWITH_V4L=ON -DWITH_LIBV4L=ON
> -OPENCV_DEPENDENCIES += libv4l
> +OPENCV_CONF_OPT += \
> +	-DWITH_V4L=ON \
> +	-DWITH_LIBV4L=$(if $(BR2_PACKAGE_LIBV4L),ON,OFF)
> +OPENCV_DEPENDENCIES += $(if $(BR2_PACKAGE_LIBV4L),libv4l)
>  else
> -OPENCV_CONF_OPT += -DWITH_V4L=OFF -DWITH_LIBV4L=OFF
> +OPENCV_CONF_OPT += \
> +	-DWITH_V4L=OFF \
> +	-DWITH_LIBV4L=OFF
>  endif
>  
>  # Installation hooks:
> -- 
> 1.9.2
> 
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