2 files changed, 34 insertions, 2 deletions

diff --git a/arch/ppc/kernel/cpu_setup_6xx.S b/arch/ppc/kernel/cpu_setup_6xx.S
index 468721d9ebd2..3fb1fb619d2c 100644
--- a/arch/ppc/kernel/cpu_setup_6xx.S
+++ b/arch/ppc/kernel/cpu_setup_6xx.S
@@ -249,8 +249,11 @@ END_FTR_SECTION_IFSET(CPU_FTR_NO_DPM)
         sync
         isync
 
-        /* Enable L2 HW prefetch
+        /* Enable L2 HW prefetch, if L2 is enabled
          */
+        mfspr   r3,SPRN_L2CR
+        andis.  r3,r3,L2CR_L2E@h
+        beqlr
         mfspr   r3,SPRN_MSSCR0
         ori     r3,r3,3
         sync
diff --git a/arch/ppc/kernel/l2cr.S b/arch/ppc/kernel/l2cr.S
index c39441048266..861115249b35 100644
--- a/arch/ppc/kernel/l2cr.S
+++ b/arch/ppc/kernel/l2cr.S
@@ -156,6 +156,26 @@ END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
                The bit moved on the 7450.....
           ****/
 
+BEGIN_FTR_SECTION
+        /* Disable L2 prefetch on some 745x and try to ensure
+         * L2 prefetch engines are idle. As explained by errata
+         * text, we can't be sure they are, we just hope very hard
+         * that well be enough (sic !). At least I noticed Apple
+         * doesn't even bother doing the dcbf's here...
+         */
+        mfspr   r4,SPRN_MSSCR0
+        rlwinm  r4,r4,0,0,29
+        sync
+        mtspr   SPRN_MSSCR0,r4
+        sync
+        isync
+        lis     r4,KERNELBASE@h
+        dcbf    0,r4
+        dcbf    0,r4
+        dcbf    0,r4
+        dcbf    0,r4
+END_FTR_SECTION_IFSET(CPU_FTR_SPEC7450)
+
         /* TODO: use HW flush assist when available */
 
         lis     r4,0x0002
@@ -230,7 +250,16 @@ END_FTR_SECTION_IFSET(CPU_FTR_SPEC7450)
         oris    r3,r3,0x8000
         mtspr   SPRN_L2CR,r3
         sync
-
+        
+        /* Enable L2 HW prefetch on 744x/745x */
+BEGIN_FTR_SECTION
+        mfspr   r3,SPRN_MSSCR0
+        ori     r3,r3,3
+        sync
+        mtspr   SPRN_MSSCR0,r3
+        sync
+        isync
+END_FTR_SECTION_IFSET(CPU_FTR_SPEC7450)
 4:
 
         /* Restore HID0[DPM] to whatever it was before */