[linux-yocto] [PATCH 1/3] arch/powerpc/kernel: Address IBM PPC476 erratum 47

[cristian.bercaru at windriver.com]

From: Sangeetha Rao <sangeetha.rao at intel.com>

Disable the BTAC in order to prevent errors in circumstances described
by IBM PPC476 erratum 47.

Signed-off-by: Sangeetha Rao <sangeetha.rao at intel.com>
---
 arch/powerpc/kernel/head_44x.S |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/powerpc/kernel/head_44x.S b/arch/powerpc/kernel/head_44x.S
index 697c30b..52c109f 100644
--- a/arch/powerpc/kernel/head_44x.S
+++ b/arch/powerpc/kernel/head_44x.S
@@ -1249,9 +1249,12 @@ clear_utlb_entry:
 	/* We configure icbi to invalidate 128 bytes at a time since the
 	 * current 32-bit kernel code isn't too happy with icache != dcache
 	 * block size
+	 * We also disable the BTAC as this can cause errors in some
+	 * circumstances (see IBM Erratum 47).
 	 */
 	mfspr	r3,SPRN_CCR0
 	oris	r3,r3,0x0020
+	ori	r3,r3,0x0040
 	mtspr	SPRN_CCR0,r3
 	isync
 
-- 
1.7.9.5