DSU: Implement workaround for errata 798953
Under certain near idle conditions, DSU may miss response transfers on
the ACE master or Peripheral port, leading to deadlock. This workaround
disables high-level clock gating of the DSU to prevent this.
Change-Id: I820911d61570bacb38dd325b3519bc8d12caa14b
Signed-off-by: Louis Mayencourt <louis.mayencourt@arm.com>
diff --git a/docs/cpu-specific-build-macros.rst b/docs/cpu-specific-build-macros.rst
index 0b58169..7b7f4cd 100644
--- a/docs/cpu-specific-build-macros.rst
+++ b/docs/cpu-specific-build-macros.rst
@@ -233,6 +233,11 @@
For DSU errata, the following build flags are defined:
+- ``ERRATA_DSU_798953``: This applies errata 798953 workaround for the
+ affected DSU configurations. This errata applies only for those DSUs that
+ revision is r0p0 (on r0p1 it is fixed). However, please note that this
+ workaround results in increased DSU power consumption on idle.
+
- ``ERRATA_DSU_936184``: This applies errata 936184 workaround for the
affected DSU configurations. This errata applies only for those DSUs that
contain the ACP interface **and** the DSU revision is older than r2p0 (on
diff --git a/include/lib/cpus/aarch64/dsu_def.h b/include/lib/cpus/aarch64/dsu_def.h
index 4ec64ee..0969acf 100644
--- a/include/lib/cpus/aarch64/dsu_def.h
+++ b/include/lib/cpus/aarch64/dsu_def.h
@@ -31,6 +31,8 @@
********************************************************************/
#define CLUSTERACTLR_EL1 S3_0_C15_C3_3
+#define CLUSTERACTLR_EL1_DISABLE_CLOCK_GATING (ULL(1) << 15)
+
/********************************************************************
* Masks applied for DSU errata workarounds
********************************************************************/
diff --git a/lib/cpus/aarch64/cortex_a55.S b/lib/cpus/aarch64/cortex_a55.S
index 1da80ef..b9a3f36 100644
--- a/lib/cpus/aarch64/cortex_a55.S
+++ b/lib/cpus/aarch64/cortex_a55.S
@@ -173,6 +173,10 @@
func cortex_a55_reset_func
mov x19, x30
+#if ERRATA_DSU_798953
+ bl errata_dsu_798953_wa
+#endif
+
#if ERRATA_DSU_936184
bl errata_dsu_936184_wa
#endif
@@ -237,6 +241,7 @@
* Report all errata. The revision variant information is at x8, where
* "report_errata" is expecting it and it doesn't corrupt it.
*/
+ report_errata ERRATA_DSU_798953, cortex_a55, dsu_798953
report_errata ERRATA_DSU_936184, cortex_a55, dsu_936184
report_errata ERRATA_A55_768277, cortex_a55, 768277
report_errata ERRATA_A55_778703, cortex_a55, 778703
diff --git a/lib/cpus/aarch64/cortex_a75.S b/lib/cpus/aarch64/cortex_a75.S
index 2040188..fda1aec 100644
--- a/lib/cpus/aarch64/cortex_a75.S
+++ b/lib/cpus/aarch64/cortex_a75.S
@@ -100,6 +100,10 @@
isb
#endif
+#if ERRATA_DSU_798953
+ bl errata_dsu_798953_wa
+#endif
+
#if ERRATA_DSU_936184
bl errata_dsu_936184_wa
#endif
@@ -186,6 +190,7 @@
report_errata ERRATA_A75_790748, cortex_a75, 790748
report_errata WORKAROUND_CVE_2017_5715, cortex_a75, cve_2017_5715
report_errata WORKAROUND_CVE_2018_3639, cortex_a75, cve_2018_3639
+ report_errata ERRATA_DSU_798953, cortex_a75, dsu_798953
report_errata ERRATA_DSU_936184, cortex_a75, dsu_936184
ldp x8, x30, [sp], #16
diff --git a/lib/cpus/aarch64/cortex_a76.S b/lib/cpus/aarch64/cortex_a76.S
index e544018..4bf6e77 100644
--- a/lib/cpus/aarch64/cortex_a76.S
+++ b/lib/cpus/aarch64/cortex_a76.S
@@ -344,9 +344,14 @@
#endif /* DYNAMIC_WORKAROUND_CVE_2018_3639 */
#endif /* WORKAROUND_CVE_2018_3639 */
+#if ERRATA_DSU_798953
+ bl errata_dsu_798953_wa
+#endif
+
#if ERRATA_DSU_936184
bl errata_dsu_936184_wa
#endif
+
ret x19
endfunc cortex_a76_reset_func
@@ -368,7 +373,7 @@
#if REPORT_ERRATA
/*
- * Errata printing function for Cortex Cortex A76. Must follow AAPCS.
+ * Errata printing function for Cortex A76. Must follow AAPCS.
*/
func cortex_a76_errata_report
stp x8, x30, [sp, #-16]!
@@ -384,6 +389,7 @@
report_errata ERRATA_A76_1130799, cortex_a76, 1130799
report_errata ERRATA_A76_1220197, cortex_a76, 1220197
report_errata WORKAROUND_CVE_2018_3639, cortex_a76, cve_2018_3639
+ report_errata ERRATA_DSU_798953, cortex_a76, dsu_798953
report_errata ERRATA_DSU_936184, cortex_a76, dsu_936184
ldp x8, x30, [sp], #16
diff --git a/lib/cpus/aarch64/dsu_helpers.S b/lib/cpus/aarch64/dsu_helpers.S
index 29870a4..100ffaa 100644
--- a/lib/cpus/aarch64/dsu_helpers.S
+++ b/lib/cpus/aarch64/dsu_helpers.S
@@ -9,6 +9,59 @@
#include <lib/cpus/errata_report.h>
/* -----------------------------------------------------------------------
+ * DSU erratum 798953 check function
+ * Checks the DSU variant, revision and configuration to determine if
+ * the erratum applies. Erratum applies on all configurations of the
+ * DSU and if revision-variant is r0p0.
+ *
+ * The erratum was fixed in r0p1.
+ *
+ * This function is called from both assembly and C environment. So it
+ * follows AAPCS.
+ *
+ * Clobbers: x0-x3
+ * -----------------------------------------------------------------------
+ */
+ .globl check_errata_dsu_798953
+ .globl errata_dsu_798953_wa
+
+func check_errata_dsu_798953
+ mov x2, #ERRATA_APPLIES
+ mov x3, #ERRATA_NOT_APPLIES
+
+ /* Check if DSU is equal to r0p0 */
+ mrs x1, CLUSTERIDR_EL1
+
+ /* DSU variant and revision bitfields in CLUSTERIDR are adjacent */
+ ubfx x0, x1, #CLUSTERIDR_REV_SHIFT,\
+ #(CLUSTERIDR_REV_BITS + CLUSTERIDR_VAR_BITS)
+ mov x1, #(0x0 << CLUSTERIDR_REV_SHIFT)
+ cmp x0, x1
+ csel x0, x2, x3, EQ
+ ret
+endfunc check_errata_dsu_798953
+
+ /* --------------------------------------------------
+ * Errata Workaround for DSU erratum #798953.
+ *
+ * Can clobber only: x0-x17
+ * --------------------------------------------------
+ */
+func errata_dsu_798953_wa
+ mov x17, x30
+ bl check_errata_dsu_798953
+ cbz x0, 1f
+
+ /* If erratum applies, disable high-level clock gating */
+ mrs x0, CLUSTERACTLR_EL1
+ orr x0, x0, #CLUSTERACTLR_EL1_DISABLE_CLOCK_GATING
+ msr CLUSTERACTLR_EL1, x0
+ isb
+1:
+ ret x17
+endfunc errata_dsu_798953_wa
+
+ /* -----------------------------------------------------------------------
* 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
diff --git a/lib/cpus/cpu-ops.mk b/lib/cpus/cpu-ops.mk
index bfee990..4deb262 100644
--- a/lib/cpus/cpu-ops.mk
+++ b/lib/cpus/cpu-ops.mk
@@ -214,6 +214,10 @@
# only to r0p0 and r1p0 of the Neoverse N1 cpu.
ERRATA_N1_1043202 ?=1
+# Flag to apply DSU erratum 798953. This erratum applies to DSUs revision r0p0.
+# Applying the workaround results in higher DSU power consumption on idle.
+ERRATA_DSU_798953 ?=0
+
# 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.
@@ -375,6 +379,10 @@
$(eval $(call assert_boolean,ERRATA_N1_1043202))
$(eval $(call add_define,ERRATA_N1_1043202))
+# Process ERRATA_DSU_798953 flag
+$(eval $(call assert_boolean,ERRATA_DSU_798953))
+$(eval $(call add_define,ERRATA_DSU_798953))
+
# Process ERRATA_DSU_936184 flag
$(eval $(call assert_boolean,ERRATA_DSU_936184))
$(eval $(call add_define,ERRATA_DSU_936184))