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>

diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c
index dedc2bd..5969e10 100644 (file)
--- 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);
        }