[PATCH] firmware: fix external firmware dependencies

[Sascha Hauer <s.hauer@pengutronix.de>]

A pbl is not rebuilt when the firmware file specified in fw-external-y
changes.

$(patsubst %.gen.o,$(obj)/%.extgen.pbl.o, $(pbl-y)) is executed before
pbl-y actually contains the contents of fw-external-y. Also we want to
do the subsitution only for the external firmware files, not for pbl-y.

To fix this use a intermediate variable pbl-fwext-y instead of pbl-y and
initialize it before usage.

Also, use $$(wildcard $(fwdir)/%) instead of $(fwdir)/% to successfully
compile when the external firmware file is missing.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 firmware/Makefile | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/firmware/Makefile b/firmware/Makefile
index 4c68817fc6..27504e9442 100644
--- a/firmware/Makefile
+++ b/firmware/Makefile
@@ -42,6 +42,7 @@ fwobjdir := $(objtree)/firmware
 
 pbl-y     := $(addsuffix .gen.o, $(pbl-firmware-y))
 obj-pbl-y := $(addsuffix .gen.o, $(firmware-y))
+pbl-fwext-y := $(addsuffix .extgen.o, $(fw-external-y))
 
 FWNAME    = $(patsubst $(obj)/%.extgen.S,%,$(patsubst $(obj)/%.gen.S,%,$@))
 FWSTR     = $(subst /,_,$(subst .,_,$(subst -,_,$(FWNAME))))
@@ -104,9 +105,9 @@ $(patsubst %.gen.o,$(obj)/%.gen.o, $(obj-pbl-y)): $(obj)/%.gen.o: $(fwdir)/%
 # The same for pbl:
 .SECONDEXPANSION:
 $(patsubst %.gen.o,$(obj)/%.gen.pbl.o, $(obj-pbl-y) $(pbl-y)): $(obj)/%.gen.pbl.o: $$(wildcard $(fwdir)/%)
-$(patsubst %.gen.o,$(obj)/%.extgen.pbl.o, $(pbl-y)): $(obj)/%.extgen.pbl.o: $(fwdir)/%
+$(patsubst %.extgen.o,$(obj)/%.extgen.pbl.o, $(pbl-fwext-y)): $(obj)/%.extgen.pbl.o: $$(wildcard $(fwdir)/%)
 
-pbl-y += $(addsuffix .extgen.o, $(fw-external-y))
+pbl-y += $(pbl-fwext-y)
 
 targets := $(patsubst $(obj)/%,%, \
                                 $(shell find $(obj) -name \*.gen.S 2>/dev/null))
-- 
2.39.2