powerpc: Initialize LPCR:DPFD on power7 to a sane default

This sets the default data stream prefetch size for operating
systems that don't set their own value in DSCR. We use 4 which
is "medium".

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/cpu_setup_power7.S b/arch/powerpc/kernel/cpu_setup_power7.S
index e801ef15d6d0..2390f6f7c478 100644
--- a/arch/powerpc/kernel/cpu_setup_power7.S
+++ b/arch/powerpc/kernel/cpu_setup_power7.S
@@ -54,6 +54,7 @@ __init_LPCR:
          *
          *   LPES = 0b01 (HSRR0/1 used for 0x500)
          *   PECE = 0b111
+         *   DPFD = 4
          *
          * Other bits untouched for now
          */
@@ -61,6 +62,12 @@ __init_LPCR:
         ori     r3,r3,(LPCR_LPES0|LPCR_LPES1)
         xori    r3,r3, LPCR_LPES0
         ori     r3,r3,(LPCR_PECE0|LPCR_PECE1|LPCR_PECE2)
+        li      r5,7
+        sldi    r5,r5,LPCR_DPFD_SH
+        andc    r3,r3,r5
+        li      r5,4
+        sldi    r5,r5,LPCR_DPFD_SH
+        or      r3,r3,r5
         mtspr   SPRN_LPCR,r3
         isync
         blr