[POWERPC] powerpc: Enable DEEPNAP power savings mode on 970MP

Without this patch, on an idle system I get:

cpu-power-0:21.638
cpu-power-1:27.102
cpu-power-2:29.343
cpu-power-3:25.784
Total: 103.8W

With this patch:

cpu-power-0:11.730
cpu-power-1:17.185
cpu-power-2:18.547
cpu-power-3:17.528
Total: 65.0W

If I lower HZ to 100, I can get it as low as:

cpu-power-0:10.938
cpu-power-1:16.021
cpu-power-2:17.245
cpu-power-3:16.145
Total: 60.2W

Another (older) Quad G5 went from 54W to 39W at HZ=250.

Coming back out of Deep Nap takes 40-70 cycles longer than coming back
from just Nap (which already takes quite a while). I don't think it'll
be a performance issue (interrupt latency on an idle system), but in
case someone does measurements feel free to report them.

Signed-off-by: Olof Johansson <olof@lixom.net>
Acked-by: Michael Buesch <mb@bu3sch.de>
Signed-off-by: Paul Mackerras <paulus@samba.org>

diff --git a/arch/powerpc/kernel/cpu_setup_ppc970.S b/arch/powerpc/kernel/cpu_setup_ppc970.S
index 652594891d58aa90f14a5a07332f2d39ca15b8f0..bf118c3857520a81eb978b016512607f49c8b611 100644 (file)
--- a/arch/powerpc/kernel/cpu_setup_ppc970.S
+++ b/arch/powerpc/kernel/cpu_setup_ppc970.S
@@ -83,6 +83,22 @@ _GLOBAL(__setup_cpu_ppc970)
        rldimi  r0,r11,52,8             /* set NAP and DPM */
        li      r11,0
        rldimi  r0,r11,32,31            /* clear EN_ATTN */
+       b       load_hids               /* Jump to shared code */
+
+
+_GLOBAL(__setup_cpu_ppc970MP)
+       /* Do nothing if not running in HV mode */
+       mfmsr   r0
+       rldicl. r0,r0,4,63
+       beqlr
+
+       mfspr   r0,SPRN_HID0
+       li      r11,0x15                /* clear DOZE and SLEEP */
+       rldimi  r0,r11,52,6             /* set DEEPNAP, NAP and DPM */
+       li      r11,0
+       rldimi  r0,r11,32,31            /* clear EN_ATTN */
+
+load_hids:
        mtspr   SPRN_HID0,r0
        mfspr   r0,SPRN_HID0
        mfspr   r0,SPRN_HID0

diff --git a/arch/powerpc/kernel/cputable.c b/arch/powerpc/kernel/cputable.c
index 95382f99440475b097420a322031b5293858492a..f02b402c66d9bdbea3adaebfb3757a902f6a37b3 100644 (file)
--- a/arch/powerpc/kernel/cputable.c
+++ b/arch/powerpc/kernel/cputable.c
@@ -41,6 +41,7 @@ extern void __setup_cpu_745x(unsigned long offset, struct cpu_spec* spec);
 #endif /* CONFIG_PPC32 */
 #ifdef CONFIG_PPC64
 extern void __setup_cpu_ppc970(unsigned long offset, struct cpu_spec* spec);
+extern void __setup_cpu_ppc970MP(unsigned long offset, struct cpu_spec* spec);
 extern void __restore_cpu_ppc970(void);
 #endif /* CONFIG_PPC64 */
 
@@ -221,7 +222,7 @@ struct cpu_spec     cpu_specs[] = {
                .icache_bsize           = 128,
                .dcache_bsize           = 128,
                .num_pmcs               = 8,
-               .cpu_setup              = __setup_cpu_ppc970,
+               .cpu_setup              = __setup_cpu_ppc970MP,
                .cpu_restore            = __restore_cpu_ppc970,
                .oprofile_cpu_type      = "ppc64/970",
                .oprofile_type          = PPC_OPROFILE_POWER4,