From 03da3ff1cfcd7774c8780d2547ba0d995f7dc03d Mon Sep 17 00:00:00 2001 From: David Woodhouse Date: Wed, 16 Sep 2015 14:10:03 +0100 Subject: [PATCH] x86/platform: Fix Geode LX timekeeping in the generic x86 build In 2007, commit 07190a08eef36 ("Mark TSC on GeodeLX reliable") bypassed verification of the TSC on Geode LX. However, this code (now in the check_system_tsc_reliable() function in arch/x86/kernel/tsc.c) was only present if CONFIG_MGEODE_LX was set. OpenWRT has recently started building its generic Geode target for Geode GX, not LX, to include support for additional platforms. This broke the timekeeping on LX-based devices, because the TSC wasn't marked as reliable: https://dev.openwrt.org/ticket/20531 By adding a runtime check on is_geode_lx(), we can also include the fix if CONFIG_MGEODEGX1 or CONFIG_X86_GENERIC are set, thus fixing the problem. Signed-off-by: David Woodhouse Cc: Andres Salomon Cc: Linus Torvalds Cc: Marcelo Tosatti Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/1442409003.131189.87.camel@infradead.org Signed-off-by: Ingo Molnar --- arch/x86/kernel/tsc.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c index 79055cf2c497..51e62d6afd9a 100644 --- a/arch/x86/kernel/tsc.c +++ b/arch/x86/kernel/tsc.c @@ -21,6 +21,7 @@ #include #include #include +#include unsigned int __read_mostly cpu_khz; /* TSC clocks / usec, not used here */ EXPORT_SYMBOL(cpu_khz); @@ -1015,15 +1016,17 @@ EXPORT_SYMBOL_GPL(mark_tsc_unstable); static void __init check_system_tsc_reliable(void) { -#ifdef CONFIG_MGEODE_LX - /* RTSC counts during suspend */ +#if defined(CONFIG_MGEODEGX1) || defined(CONFIG_MGEODE_LX) || defined(CONFIG_X86_GENERIC) + if (is_geode_lx()) { + /* RTSC counts during suspend */ #define RTSC_SUSP 0x100 - unsigned long res_low, res_high; + unsigned long res_low, res_high; - rdmsr_safe(MSR_GEODE_BUSCONT_CONF0, &res_low, &res_high); - /* Geode_LX - the OLPC CPU has a very reliable TSC */ - if (res_low & RTSC_SUSP) - tsc_clocksource_reliable = 1; + rdmsr_safe(MSR_GEODE_BUSCONT_CONF0, &res_low, &res_high); + /* Geode_LX - the OLPC CPU has a very reliable TSC */ + if (res_low & RTSC_SUSP) + tsc_clocksource_reliable = 1; + } #endif if (boot_cpu_has(X86_FEATURE_TSC_RELIABLE)) tsc_clocksource_reliable = 1; -- 2.20.1