DSU erratum 936184 workaround

If the system is in near idle conditions, this erratum could cause a
deadlock or data corruption. This patch applies the workaround that
prevents this.

This DSU erratum affects only the DSUs that contain the ACP interface
and it was fixed in r2p0. The workaround is applied only to the DSUs
that are actually affected.

Link to respective Arm documentation:
http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.epm138168/index.html

Change-Id: I033213b3077685130fc1e3f4f79c4d15d7483ec9
Signed-off-by: John Tsichritzis <john.tsichritzis@arm.com>
diff --git a/lib/cpus/cpu-ops.mk b/lib/cpus/cpu-ops.mk
index 456e3e5..40a8ac7 100644
--- a/lib/cpus/cpu-ops.mk
+++ b/lib/cpus/cpu-ops.mk
@@ -123,6 +123,11 @@
 # only to r0p0 and r1p0 of the Ares cpu.
 ERRATA_ARES_1043202	?=1
 
+# Flag to apply DSU erratum 936184. This erratum applies to DSUs containing
+# the ACP interface and revision < r2p0. Applying the workaround results in
+# higher DSU power consumption on idle.
+ERRATA_DSU_936184	?=0
+
 # Process ERRATA_A53_826319 flag
 $(eval $(call assert_boolean,ERRATA_A53_826319))
 $(eval $(call add_define,ERRATA_A53_826319))
@@ -187,6 +192,10 @@
 $(eval $(call assert_boolean,ERRATA_ARES_1043202))
 $(eval $(call add_define,ERRATA_ARES_1043202))
 
+# Process ERRATA_DSU_936184 flag
+$(eval $(call assert_boolean,ERRATA_DSU_936184))
+$(eval $(call add_define,ERRATA_DSU_936184))
+
 # Errata build flags
 ifneq (${ERRATA_A53_843419},0)
 TF_LDFLAGS_aarch64	+= --fix-cortex-a53-843419