Merge pull request #1536 from jts-arm/dsu
DSU erratum 936184 workaround: bug fix
diff --git a/lib/cpus/aarch64/dsu_helpers.S b/lib/cpus/aarch64/dsu_helpers.S
index 293ed24..152a3da 100644
--- a/lib/cpus/aarch64/dsu_helpers.S
+++ b/lib/cpus/aarch64/dsu_helpers.S
@@ -8,15 +8,19 @@
#include <dsu_def.h>
#include <errata_report.h>
-/*
- * DSU erratum 936184
- * Check the DSU variant, revision and configuration to determine if the
- * erratum applies. This erratum was fixed in r2p0.
+/* -----------------------------------------------------------------------
+ * DSU erratum 936184 check function
+ * Checks the DSU variant, revision and configuration to determine if
+ * the erratum applies. Erratum applies if ACP interface is present
+ * in the DSU and revision-variant < r2p0.
+ *
+ * The erratum was fixed in r2p0.
*
* This function is called from both assembly and C environment. So it
* follows AAPCS.
*
* Clobbers: x0-x3
+ * -----------------------------------------------------------------------
*/
.globl check_errata_dsu_936184
.globl errata_dsu_936184_wa
@@ -25,7 +29,7 @@
mov x2, #ERRATA_NOT_APPLIES
mov x3, #ERRATA_APPLIES
- /* Erratum applies only if ACP interface is present in DSU */
+ /* Erratum applies only if DSU has the ACP interface */
mov x0, x2
mrs x1, CLUSTERCFR_EL1
ubfx x1, x1, #CLUSTERCFR_ACP_SHIFT, #1
@@ -44,8 +48,14 @@
ret
endfunc check_errata_dsu_936184
+/* --------------------------------------------------
+ * Errata Workaround for DSU erratum #936184.
+ *
+ * Can clobber only: x0-x17
+ * --------------------------------------------------
+ */
func errata_dsu_936184_wa
- mov x20, x30
+ mov x17, x30
bl check_errata_dsu_936184
cbz x0, 1f
@@ -56,5 +66,5 @@
msr CLUSTERACTLR_EL1, x0
isb
1:
- ret x20
+ ret x17
endfunc errata_dsu_936184_wa