ARM: smp: Introduce ARCH_HAS_COMMON_CORES_CLOCK to speed-up boot

Commit Message

Santosh Shilimkar Jan. 20, 2011, 9:42 a.m. UTC

None

Patch

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 5cff165..8944639 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -823,6 +823,7 @@  config ARCH_U300
 config ARCH_U8500
 	bool "ST-Ericsson U8500 Series"
 	select CPU_V7
+	select ARCH_HAS_COMMON_CORES_CLOCK
 	select ARM_AMBA
 	select GENERIC_CLOCKEVENTS
 	select CLKDEV_LOOKUP
@@ -1418,6 +1419,10 @@  config ARCH_SPARSEMEM_DEFAULT
 config ARCH_SELECT_MEMORY_MODEL
 	def_bool ARCH_SPARSEMEM_ENABLE
 
+config ARCH_HAS_COMMON_CORES_CLOCK
+      bool
+      depends on SMP
+
 config HIGHMEM
 	bool "High Memory Support (EXPERIMENTAL)"
 	depends on MMU && EXPERIMENTAL
diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index 4539ebc..8e72b11 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -270,6 +270,20 @@  static void __cpuinit smp_store_cpu_info(unsigned int cpuid)
 }
 
 /*
+ * Skip the secondary calibration on architectures sharing clock
+ * with primary cpu. Archs can select ARCH_HAS_COMMON_CORES_CLOCK
+ * for this.
+ */
+static inline int skip_secondary_calibrate(void)
+{
+#ifdef CONFIG_ARCH_HAS_COMMON_CORES_CLOCK
+	return true;
+#else
+	return false;
+#endif
+}
+
+/*
  * This is the secondary CPU boot entry.  We're using this CPUs
  * idle thread stack, but a set of temporary page tables.
  */
@@ -312,7 +326,8 @@  asmlinkage void __cpuinit secondary_start_kernel(void)
 	 */
 	percpu_timer_setup();
 
-	calibrate_delay();
+	if (!skip_secondary_calibrate())
+		calibrate_delay();
 
 	smp_store_cpu_info(cpu);
 
@@ -332,14 +347,19 @@  void __init smp_cpus_done(unsigned int max_cpus)
 	int cpu;
 	unsigned long bogosum = 0;
 
-	for_each_online_cpu(cpu)
-		bogosum += per_cpu(cpu_data, cpu).loops_per_jiffy;
+	if (!skip_secondary_calibrate()) {
+		for_each_online_cpu(cpu)
+			bogosum += per_cpu(cpu_data, cpu).loops_per_jiffy;
 
-	printk(KERN_INFO "SMP: Total of %d processors activated "
-	       "(%lu.%02lu BogoMIPS).\n",
-	       num_online_cpus(),
-	       bogosum / (500000/HZ),
-	       (bogosum / (5000/HZ)) % 100);
+		printk(KERN_INFO "SMP: Total of %d processors activated "
+		       "(%lu.%02lu BogoMIPS).\n",
+			num_online_cpus(),
+			bogosum / (500000/HZ),
+			(bogosum / (5000/HZ)) % 100);
+	} else {
+		printk(KERN_INFO "SMP: Total of %d processors activated.\n",
+			num_online_cpus());
+	}
 }
 
 void __init smp_prepare_boot_cpu(void)
diff --git a/arch/arm/mach-omap2/Kconfig b/arch/arm/mach-omap2/Kconfig
index 1a2cf62..e6ad15d 100644
--- a/arch/arm/mach-omap2/Kconfig
+++ b/arch/arm/mach-omap2/Kconfig
@@ -43,6 +43,7 @@  config ARCH_OMAP4
 	default y
 	depends on ARCH_OMAP2PLUS
 	select CPU_V7
+	select ARCH_HAS_COMMON_CORES_CLOCK
 	select ARM_GIC
 	select PL310_ERRATA_588369
 	select ARM_ERRATA_720789