x86, hpet: Disable per-cpu hpet timer if ARAT is supported

If CPU support always running local APIC timer, per-cpu hpet
timer could be disabled, which is useless and wasteful in such
case. Let's leave the timers to others.

The effect is that we reserve less timers.

Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Cc: venkatesh.pallipadi@intel.com
LKML-Reference: <20090812031612.GA10062@sli10-desk.sh.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 10 insertions, 2 deletions

diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c
index dedc2bddf7a5..5969e1078fc2 100644
--- a/arch/x86/kernel/hpet.c
+++ b/arch/x86/kernel/hpet.c
@@ -584,6 +584,8 @@ static void hpet_msi_capability_lookup(unsigned int start_timer)
         unsigned int num_timers_used = 0;
         int i;
 
+        if (boot_cpu_has(X86_FEATURE_ARAT))
+                return;
         id = hpet_readl(HPET_ID);
 
         num_timers = ((id & HPET_ID_NUMBER) >> HPET_ID_NUMBER_SHIFT);
@@ -872,10 +874,8 @@ int __init hpet_enable(void)
 
         if (id & HPET_ID_LEGSUP) {
                 hpet_legacy_clockevent_register();
-                hpet_msi_capability_lookup(2);
                 return 1;
         }
-        hpet_msi_capability_lookup(0);
         return 0;
 
 out_nohpet:
@@ -908,9 +908,17 @@ static __init int hpet_late_init(void)
         if (!hpet_virt_address)
                 return -ENODEV;
 
+        if (hpet_readl(HPET_ID) & HPET_ID_LEGSUP)
+                hpet_msi_capability_lookup(2);
+        else
+                hpet_msi_capability_lookup(0);
+
         hpet_reserve_platform_timers(hpet_readl(HPET_ID));
         hpet_print_config();
 
+        if (boot_cpu_has(X86_FEATURE_ARAT))
+                return 0;
+
         for_each_online_cpu(cpu) {
                 hpet_cpuhp_notify(NULL, CPU_ONLINE, (void *)(long)cpu);
         }