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

diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c
index 8c57dbf15e3b3586e258727dea773fc2c74759e6..74756c0a3a1009f0ae24a11b0fcc8133cebd45e1 100644 (file)
--- 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;
 }
 
 /**