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Subject[PATCH 2/2] ARM: errata: add support for A12/A17 errata CR711784
Date
This adds a code for turning on chicken bit 11, which appears to avoid
a potential CPU deadlock that could occur. The exact set of
instruction needed to trigger this errata is not totaly known but we
have a high level of confidence that the problem is fixed by setting
chicken bit 11.

All details are in http://crbug.com/711784

This erratum has no known number and thus I have tagged it CR711784
(after the Chrome OS bug number). I have created separate A12 / A17
configs to match how the rest of the A12 / A17 errata is handled.

Signed-off-by: Douglas Anderson <dianders@chromium.org>
---

arch/arm/Kconfig | 18 ++++++++++++++++++
arch/arm/mm/proc-v7.S | 10 ++++++++++
2 files changed, 28 insertions(+)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 4376fe74f95e..34ec9039206b 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1181,6 +1181,13 @@ config ARM_ERRATA_857271
hang. The workaround is expected to have a negligible performance
impact.

+config ARM_ERRATA_CR711784_A12
+ bool "ARM errata: A12: conditional instructions can lead to a CPU hang"
+ depends on CPU_V7
+ help
+ This option enables the workaround for a Cortex-A12 erratum without a
+ number. The problems are best described in https://crbug.com/711784
+
config ARM_ERRATA_852421
bool "ARM errata: A17: DMB ST might fail to create order between stores"
depends on CPU_V7
@@ -1212,6 +1219,17 @@ config ARM_ERRATA_857272
config option from the A12 erratum due to the way errata are checked
for and handled.

+config ARM_ERRATA_CR711784_A17
+ bool "ARM errata: A17: conditional instructions can lead to a CPU hang"
+ depends on CPU_V7
+ help
+ This option enables the workaround for a Cortex-A17 erratum without a
+ number. The problems are best described in https://crbug.com/711784
+ This erratum is not known to be fixed in any A17 revision.
+ This is identical to Cortex-A12 erratum CR711784. It is a separate
+ config option from the A12 erratum due to the way errata are checked
+ for and handled.
+
endmenu

source "arch/arm/common/Kconfig"
diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S
index cd2accbab844..a5156ea734ee 100644
--- a/arch/arm/mm/proc-v7.S
+++ b/arch/arm/mm/proc-v7.S
@@ -396,6 +396,11 @@ __ca12_errata:
mrc p15, 0, r10, c15, c0, 1 @ read diagnostic register
orr r10, r10, #1 << 10 @ set bit #10
mcr p15, 0, r10, c15, c0, 1 @ write diagnostic register
+#endif
+#ifdef CONFIG_ARM_ERRATA_CR711784_A12
+ mrc p15, 0, r10, c15, c0, 1 @ read diagnostic register
+ orr r10, r10, #1 << 11 @ set bit #11
+ mcr p15, 0, r10, c15, c0, 1 @ write diagnostic register
#endif
b __errata_finish

@@ -416,6 +421,11 @@ __ca17_errata:
mrc p15, 0, r10, c15, c0, 1 @ read diagnostic register
orr r10, r10, #1 << 10 @ set bit #10
mcr p15, 0, r10, c15, c0, 1 @ write diagnostic register
+#endif
+#ifdef CONFIG_ARM_ERRATA_CR711784_A17
+ mrc p15, 0, r10, c15, c0, 1 @ read diagnostic register
+ orr r10, r10, #1 << 11 @ set bit #11
+ mcr p15, 0, r10, c15, c0, 1 @ write diagnostic register
#endif
b __errata_finish

--
2.21.0.593.g511ec345e18-goog
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