x86: Skip verification by the watchdog for TSC clocksource.

[linux-2.6-omap-h63xx.git] / arch / x86 / kernel / tsc.c

diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 6dbf0bcb44a8bc2d56b6778aa12a22484e7f691b..ee01cd96b5e12e6b94a7f5d7c20f6f839b4a8d10 100644 (file)
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -32,6 +32,7 @@ static int tsc_unstable;
    erroneous rdtsc usage on !cpu_has_tsc processors */
 static int tsc_disabled = -1;
 
+static int tsc_clocksource_reliable;
 /*
  * Scheduler clock - returns current time in nanosec units.
  */
@@ -99,6 +100,15 @@ int __init notsc_setup(char *str)
 
 __setup("notsc", notsc_setup);
 
+static int __init tsc_setup(char *str)
+{
+       if (!strcmp(str, "reliable"))
+               tsc_clocksource_reliable = 1;
+       return 1;
+}
+
+__setup("tsc=", tsc_setup);
+
 #define MAX_RETRIES     5
 #define SMI_TRESHOLD    50000
 
@@ -738,24 +748,21 @@ static struct dmi_system_id __initdata bad_tsc_dmi_table[] = {
        {}
 };
 
-/*
- * Geode_LX - the OLPC CPU has a possibly a very reliable TSC
- */
+static void __init check_system_tsc_reliable(void)
+{
 #ifdef CONFIG_MGEODE_LX
-/* RTSC counts during suspend */
+       /* RTSC counts during suspend */
 #define RTSC_SUSP 0x100
-
-static void __init check_geode_tsc_reliable(void)
-{
        unsigned long res_low, res_high;
 
        rdmsr_safe(MSR_GEODE_BUSCONT_CONF0, &res_low, &res_high);
+       /* Geode_LX - the OLPC CPU has a possibly a very reliable TSC */
        if (res_low & RTSC_SUSP)
-               clocksource_tsc.flags &= ~CLOCK_SOURCE_MUST_VERIFY;
-}
-#else
-static inline void check_geode_tsc_reliable(void) { }
+               tsc_clocksource_reliable = 1;
 #endif
+       if (boot_cpu_has(X86_FEATURE_TSC_RELIABLE))
+               tsc_clocksource_reliable = 1;
+}
 
 /*
  * Make an educated guess if the TSC is trustworthy and synchronized
@@ -790,6 +797,8 @@ static void __init init_tsc_clocksource(void)
 {
        clocksource_tsc.mult = clocksource_khz2mult(tsc_khz,
                        clocksource_tsc.shift);
+       if (tsc_clocksource_reliable)
+               clocksource_tsc.flags &= ~CLOCK_SOURCE_MUST_VERIFY;
        /* lower the rating if we already know its unstable: */
        if (check_tsc_unstable()) {
                clocksource_tsc.rating = 0;
@@ -850,7 +859,7 @@ void __init tsc_init(void)
        if (unsynchronized_tsc())
                mark_tsc_unstable("TSCs unsynchronized");
 
-       check_geode_tsc_reliable();
+       check_system_tsc_reliable();
        init_tsc_clocksource();
 }