Subject: [PATCH] powerpc: enable NAP only on cpus who support it to avoid memory corruption

From: Olaf Hering <[email-masked]>
Date: Sat, 11 Mar 2006 22:58:40 +0100

commit 51d3082fe6e55aecfa17113dbe98077c749f724c enabled NAP unconditinally
on all powermacs. Early G3 cpus can not use it, the result is memory corruption.

Only enable powersave_nap in one place: probe_motherboard()
ppc32 gets nap if the cpu supports it
ppc32 smp gets no nap
ppc64 gets nap unconditionally

---
 arch/powerpc/platforms/powermac/feature.c |    8 +++++++-
 arch/powerpc/platforms/powermac/setup.c   |    4 ----
 arch/powerpc/platforms/powermac/smp.c     |    4 ----
 3 files changed, 7 insertions(+), 9 deletions(-)

Index: linux-2.6.16-rc5-olh/arch/powerpc/platforms/powermac/feature.c
===================================================================
--- linux-2.6.16-rc5-olh.orig/arch/powerpc/platforms/powermac/feature.c
+++ linux-2.6.16-rc5-olh/arch/powerpc/platforms/powermac/feature.c
@@ -2513,8 +2513,11 @@ found:
 		/* Nap mode not supported if flush-on-lock property is present */
 		if (get_property(np, "flush-on-lock", NULL))
 			break;
+
+#ifndef CONFIG_SMP
+		/* 32 bits SMP can't NAP */
 		powersave_nap = 1;
-		printk(KERN_INFO "Processor NAP mode on idle enabled.\n");
+#endif
 		break;
 	}
 
@@ -2526,6 +2529,9 @@ found:
 #ifdef CONFIG_POWER4
 	powersave_nap = 1;
 #endif
+	if (powersave_nap)
+		printk(KERN_INFO "Using native/NAP idle loop\n");
+
 	/* Check for "mobile" machine */
 	if (model && (strncmp(model, "PowerBook", 9) == 0
 		   || strncmp(model, "iBook", 5) == 0))
Index: linux-2.6.16-rc5-olh/arch/powerpc/platforms/powermac/setup.c
===================================================================
--- linux-2.6.16-rc5-olh.orig/arch/powerpc/platforms/powermac/setup.c
+++ linux-2.6.16-rc5-olh/arch/powerpc/platforms/powermac/setup.c
@@ -621,10 +621,6 @@ static void __init pmac_init_early(void)
 	/* Probe motherboard chipset */
 	pmac_feature_init();
 
-	/* We can NAP */
-	powersave_nap = 1;
-	printk(KERN_INFO "Using native/NAP idle loop\n");
-
 	/* Initialize debug stuff */
 	udbg_scc_init(!!strstr(cmd_line, "sccdbg"));
 	udbg_adb_init(!!strstr(cmd_line, "btextdbg"));
Index: linux-2.6.16-rc5-olh/arch/powerpc/platforms/powermac/smp.c
===================================================================
--- linux-2.6.16-rc5-olh.orig/arch/powerpc/platforms/powermac/smp.c
+++ linux-2.6.16-rc5-olh/arch/powerpc/platforms/powermac/smp.c
@@ -739,10 +739,6 @@ static void __init smp_core99_setup(int 
 			smp_hw_index[i] = i;
 	}
 #endif
-
-	/* 32 bits SMP can't NAP */
-	if (!machine_is_compatible("MacRISC4"))
-		powersave_nap = 0;
 }
 
 static int __init smp_core99_probe(void)