fix(cpus): workaround for Cortex-X4 erratum 3076789
Cortex-X4 erratum 3076789 is a Cat B erratum that is present
in revisions r0p0, r0p1 and is fixed in r0p2.
The workaround is to set chicken bits CPUACTLR3_EL1[14:13]=0b11
and CPUACTLR_EL1[52] = 1.
Expected performance degradation is < 0.5%, but isolated
benchmark components might see higher impact.
SDEN documentation:
https://developer.arm.com/documentation/SDEN2432808/latest
Change-Id: Ib100bfab91efdb6330fdcdac127bcc5732d59196
Signed-off-by: Ryan Everett <ryan.everett@arm.com>
diff --git a/lib/cpus/cpu-ops.mk b/lib/cpus/cpu-ops.mk
index 2cbbdd2..4c20785 100644
--- a/lib/cpus/cpu-ops.mk
+++ b/lib/cpus/cpu-ops.mk
@@ -843,6 +843,10 @@
# to revisions r0p0 and r0p1 of the Cortex-X4 cpu. It is fixed in r0p2.
CPU_FLAG_LIST += ERRATA_X4_2897503
+# Flag to apply erratum 3076789 workaround on reset. This erratum applies
+# to revisions r0p0 and r0p1 of the Cortex-X4 cpu. It is fixed in r0p2.
+CPU_FLAG_LIST += ERRATA_X4_3076789
+
# Flag to apply erratum 1922240 workaround during reset. This erratum applies
# to revision r0p0 of the Cortex-A510 cpu and is fixed in r0p1.
CPU_FLAG_LIST += ERRATA_A510_1922240