[ARM] 3967/1: xsc3: make branch predication configurable on xsc3

Remove BTB_ENABLE from proc-xsc3.S

On some early revisions of xsc3 enabling the branch target buffer can cause
crashes, see erratum #42.

Cc: Lennert Buytenhek <buytenh@wantstofly.org>

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

2 files changed, 1 insertions, 8 deletions

diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig
index c0bfb8212b77..efebd6050285 100644
--- a/arch/arm/mm/Kconfig
+++ b/arch/arm/mm/Kconfig
@@ -580,7 +580,7 @@ config CPU_CACHE_ROUND_ROBIN
 
 config CPU_BPREDICT_DISABLE
         bool "Disable branch prediction"
-        depends on CPU_ARM1020 || CPU_V6
+        depends on CPU_ARM1020 || CPU_V6 || CPU_XSC3
         help
           Say Y here to disable branch prediction.  If unsure, say N.
 
diff --git a/arch/arm/mm/proc-xsc3.S b/arch/arm/mm/proc-xsc3.S
index 85c3523d0a95..1ef564d0957f 100644
--- a/arch/arm/mm/proc-xsc3.S
+++ b/arch/arm/mm/proc-xsc3.S
@@ -57,11 +57,6 @@
 #define L2_CACHE_ENABLE 1
 
 /*
- * Enable the Branch Target Buffer (can cause crashes, see erratum #42.)
- */
-#define BTB_ENABLE      0
-
-/*
  * This macro is used to wait for a CP15 write and is needed
  * when we have to ensure that the last operation to the co-pro
  * was completed before continuing with operation.
@@ -434,9 +429,7 @@ __xsc3_setup:
         mrc     p15, 0, r0, c1, c0, 0           @ get control register
         bic     r0, r0, r5                      @ .... .... .... ..A.
         orr     r0, r0, r6                      @ .... .... .... .C.M
-#if BTB_ENABLE
         orr     r0, r0, #0x00000800             @ ..VI Z..S .... ....
-#endif
 #if L2_CACHE_ENABLE
         orr     r0, r0, #0x04000000             @ L2 enable
 #endif