New patch to review for coreboot: soc/intel/apollolake: Set default memory type to uncacheable

[Furquan Shaikh]

Furquan Shaikh ([e-mail]) just uploaded a new patch set to gerrit, which you can find at https://review.coreboot.org/14428

-gerrit

commit df8473d4a5bd79bd3b8b36a9fb87df213f525b26
Author: Furquan Shaikh 
Date:   Tue Apr 19 15:49:23 2016 -0700

soc/intel/apollolake: Set default memory type to uncacheable

Set the default memory type in MTRRCap register to 0. This ensures
    that even if the MTRR Enable bit is set in MTRRCap register, the
    default memory type is still uncacheable.

Change-Id: I63e7993f8b65dabbab60e7c1bb8d6d89ef4da9ee
    Signed-off-by: Furquan Shaikh 
---
 src/soc/intel/apollolake/bootblock/cache_as_ram.S | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/soc/intel/apollolake/bootblock/cache_as_ram.S b/src/soc/intel/apollolake/bootblock/cache_as_ram.S
index 9d2bba0..cd301ac 100644
--- a/src/soc/intel/apollolake/bootblock/cache_as_ram.S
+++ b/src/soc/intel/apollolake/bootblock/cache_as_ram.S
@@ -63,7 +63,9 @@ clear_var_mtrr:
    /* Configure default memory type to uncacheable (UC) */
    mov	$MTRR_DEF_TYPE_MSR, %ecx
    rdmsr
-	and	$MTRR_DEF_TYPE_MASK, %eax
+	/* Clear enable bits and set default type to UC. */
+	and	$~(MTRR_DEF_TYPE_MASK | MTRR_DEF_TYPE_EN | \
+		   MTRR_DEF_TYPE_FIX_EN), %eax
    wrmsr

post_code(0x24)