From 44b5be5733e119300115b98409cbcf9a45b8d3f1 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Sun, 23 Jun 2019 15:23:52 +0200
Subject: [PATCH] x86/hpet: Simplify counter validation

There is no point to loop for 200k TSC cycles to check afterwards whether
the HPET counter is working. Read the counter inside of the loop and break
out when the counter value changed.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Cc: Ashok Raj <ashok.raj@intel.com>
Cc: Andi Kleen <andi.kleen@intel.com>
Cc: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Ravi Shankar <ravi.v.shankar@intel.com>
Link: https://lkml.kernel.org/r/20190623132435.149535103@linutronix.de
---
 arch/x86/kernel/hpet.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c
index 8c57dbf..74756c0 100644
--- a/arch/x86/kernel/hpet.c
+++ b/arch/x86/kernel/hpet.c
@@ -853,15 +853,13 @@ static bool __init hpet_counting(void)
 	 * 1 GHz == 200us
 	 */
 	do {
-		rep_nop();
+		if (t1 != hpet_readl(HPET_COUNTER))
+			return true;
 		now = rdtsc();
 	} while ((now - start) < 200000UL);
 
-	if (t1 == hpet_readl(HPET_COUNTER)) {
-		pr_warn("Counter not counting. HPET disabled\n");
-		return false;
-	}
-	return true;
+	pr_warn("Counter not counting. HPET disabled\n");
+	return false;
 }
 
 /**
-- 
2.7.4