On Tue, Feb 23, 2016 at 8:54 AM, Markus Pargmann [off-list ref] wrote:

Add include paths to the Makefile so that linux/gpio.h can be found even
on systems without this header.

Signed-off-by: Markus Pargmann <redacted>

(...)

-CFLAGS += -Wall -g -D_GNU_SOURCE
+CFLAGS += -Wall -g -D_GNU_SOURCE -I ../include -I ../../include/uapi

This is probably not how userspace compilation is supposed
to work. The way I understand it, userspace programs from tools/*
should be compiled like this:

make headers_install ARCH=foo INSTALL_HDR_PATH=<bar>
cd tools/gpio
make CFLAGS="$CFLAGS -I<bar>"

The reason being that UAPI files can differ after install depending
on arch.

Yours,
Linus Walleij