cts: Fix back-to-back build

Currently eCTS suites share the same directory (e.g. build/stm32l476g
-eval) to put build artifacts even though some files (e.g. board.c)
compile differently suite to suite. So, if cts-i2c-stm32l476g-eval is
built, followed by cts-gpio-stm32l476g-eval, build fails or produces
incorrect binary.

This patch makes eCTS create different directories for each suite.
As a bonus, we can now builds eCTS suites in parallel.

BUG=chromium:654549
BRANCH=none
TEST=make buildall -j (with uncommitted change)

Change-Id: I4abedc917787be5f79b97e0e50d0d08e01bd5f9d
Signed-off-by: Daisuke Nojiri <dnojiri@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/398281

1 files changed, 5 insertions, 0 deletions

diff --git a/Makefile b/Makefile
index 3b5c4e70d4..912c6ab64d 100644
--- a/Makefile
+++ b/Makefile
@@ -23,7 +23,12 @@ endif
 PROJECT?=ec
 
 # Output directory for build objects
+ifdef CTS_MODULE
+# CTS builds need different directories per board per suite.
+out?=build/$(BOARD)/cts_$(CTS_MODULE)
+else
 out?=build/$(BOARD)
+endif
 
 # File containing configuration information
 config=$(out)/.config