[Buildroot] [PATCH 2/2] package/libftdi: fix libftdi.pc

[Thomas Petazzoni <thomas.petazzoni@free-electrons.com>]

Dear Samuel Martin,

On Mon, 12 Jan 2015 22:26:05 +0100, Samuel Martin wrote:

> +diff --git a/libftdi.pc.in b/libftdi.pc.in
> +index 2061b91..95eb491 100644
> +--- a/libftdi.pc.in
> ++++ b/libftdi.pc.in
> +@@ -6,6 +6,7 @@ includedir=@includedir@
> + Name: libftdi
> + Description: Library to program and control the FTDI USB controller
> + Requires:
> ++Requires.private: libusb
> + Version: @VERSION@
> + Libs: -L${libdir} -lftdi -lusb
> + Cflags: -I${includedir}

Are you sure this is the right fix? I believe the right fix is rather:

-Requires:
+Requires: libusb
...
-Libs: -L${libdir} -lftdi -lusb
+Libs: -L${libdir} -lftdi

This properly declares the fact that libftdi requires libusb. And
libusb.pc already has the appropriate Requires.private field on
libusb-1.0. With this change, you get what I believe is the correct
behavior:

When linking dynamically, we're only linked against -lusb (i.e the
libusb-compat library) :

$ ./output/host/usr/bin/pkg-config --libs libftdi
-lftdi -L/home/thomas/projets/buildroot/output/host/usr/arm-buildroot-linux-uclibcgnueabi/sysroot/usr/lib -lusb  

When linking statically, we correct get both -lusb and -lusb-1.0:

$ ./output/host/usr/bin/pkg-config --static --libs libftdi
-lftdi -lusb -L/home/thomas/projets/buildroot/output/host/usr/arm-buildroot-linux-uclibcgnueabi/sysroot/usr/lib -lusb-1.0 -pthread

This is more or less what was done upstream at
http://developer.intra2net.com/git/?p=libftdi;a=commitdiff;h=ac5790a7af9ffb45c00bde056b308643cd52537e,
though this commit was after they switched to libusb instead of
libusb-compat.

Thanks,

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com