[PATCH v2] kernel-devicetree: Introduce KERNEL_DTC_FLAGS to pass dtc flags

[PATCH v2] kernel-devicetree: Introduce KERNEL_DTC_FLAGS to pass dtc flags

[Ovidiu Panait]

Currently DTC_FLAGS kernel makefile parameter can be specified directly on the
command line by adding it to KERNEL_EXTRA_ARGS. However, this prevents
scripts/Makefile.lib logic from appending flags that silence dtc warnings (all
assignments done from within a makefile, to a variable specified on the command
line, are ignored).

Because of this, the do_compile log is cluttered with dtc warnings that should
only be printed when compiling with W="123":
...
/soc: node has a reg or ranges property, but no unit name
/soc/gpu: missing or empty reg/ranges property
/soc/firmware/gpio: missing or empty reg/ranges property
...

To fix this, introduce the dedicated KERNEL_DTC_FLAGS variable to hold
dtc flags and export DTC_FLAGS in the environment before generating the dtbs
(make allows "+=" operations on variables that come from the environment, so
the warnings are silenced properly).

Signed-off-by: Ovidiu Panait <ovidiu.panait@windriver.com>
---
v2 updates:
- Rename KERNEL_DEVICETREE_FLAGS -> KERNEL_DTC_FLAGS
- Use "-n <var>" instead of "! -z <var>" inside if test

 meta/classes/kernel-devicetree.bbclass | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/meta/classes/kernel-devicetree.bbclass b/meta/classes/kernel-devicetree.bbclass
index 81dda8003f..d4f8864200 100644
--- a/meta/classes/kernel-devicetree.bbclass
+++ b/meta/classes/kernel-devicetree.bbclass
@@ -9,6 +9,9 @@ FILES_${KERNEL_PACKAGE_NAME}-image-zimage-bundle = "/${KERNEL_IMAGEDEST}/zImage-
 # Generate kernel+devicetree bundle
 KERNEL_DEVICETREE_BUNDLE ?= "0"
 
+# dtc flags passed via DTC_FLAGS env variable
+KERNEL_DTC_FLAGS ?= ""
+
 normalize_dtb () {
 	dtb="$1"
 	if echo $dtb | grep -q '/dts/'; then
@@ -50,6 +53,10 @@ do_configure_append() {
 }
 
 do_compile_append() {
+	if [ -n "${KERNEL_DTC_FLAGS}" ]; then
+		export DTC_FLAGS="${KERNEL_DTC_FLAGS}"
+	fi
+
 	for dtbf in ${KERNEL_DEVICETREE}; do
 		dtb=`normalize_dtb "$dtbf"`
 		oe_runmake $dtb CC="${KERNEL_CC} $cc_extra " LD="${KERNEL_LD}" ${KERNEL_EXTRA_ARGS}
-- 
2.17.1