[PATCH 2/3] x86/time: Unconditionally register legacy timer interrupt

[Peter Zijlstra <peterz@infradead.org>]

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Even without a PIC/PIT we need the legacy timer interrupt for HPET in
legacy replacement mode.

Cc: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 arch/x86/kernel/time.c |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

--- a/arch/x86/kernel/time.c
+++ b/arch/x86/kernel/time.c
@@ -69,9 +69,12 @@ static struct irqaction irq0  = {
 
 static void __init setup_default_timer_irq(void)
 {
-	if (!nr_legacy_irqs())
-		return;
-	setup_irq(0, &irq0);
+	/*
+	 * Unconditionally register the legacy timer; even without legacy
+	 * PIC/PIT we need this for the HPET0 in legacy replacement mode.
+	 */
+	if (setup_irq(0, &irq0))
+		pr_info("Failed to register legacy timer interrupt\n");
 }
 
 /* Default timer init function */