From 80ac2912f846c01d702774bb6aa7100ec71e88b9 Mon Sep 17 00:00:00 2001 From: Kumar Gala Date: Wed, 31 Aug 2005 14:54:47 +1000 Subject: [PATCH] [PATCH] ppc: L2 cache prefetch fixes on 745x We run into problems if we blindly enable L2 prefetching without checking that the L2 cache is actually enabled. Additionaly, if we disable the L2 cache we need to ensure that we disable L2 prefetching. Signed-off-by: Kumar Gala Signed-off-by: Benjamin Herrenschmidt Signed-off-by: Linus Torvalds --- arch/ppc/kernel/cpu_setup_6xx.S | 5 ++++- arch/ppc/kernel/l2cr.S | 31 ++++++++++++++++++++++++++++++- 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 */