[PATCH 2/2] x86/apic: check global clockevent in lapic timer setup

[Jacob Pan]

Global clockevent is needed to calibrate local apic timer.
This patch makes sure we have a valid global clockevent prior
to lapic timer setup.
Non-pc x86 mid platform with per cpu platform timer may not
have a global clockevent device.

Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxx>
---
 arch/x86/kernel/apic/apic.c |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index aa57c07..7e7aee1 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -724,6 +724,13 @@ static int __init calibrate_APIC_clock(void)
  */
 void __init setup_boot_APIC_clock(void)
 {
+	/* global clockevent is needed for calibration */
+	if (!global_clock_event) {
+		apic_printk(APIC_DEBUG,
+				"no global clockevent for calibration\n");
+		return;
+	}
+
 	/*
 	 * The local apic timer can be disabled via the kernel
 	 * commandline or from the CPU detection code. Register the lapic
-- 
1.6.5.3

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