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- From: David Woodhouse <[email protected]>
- Date: Thu, 17 Sep 2015 10:16:54 +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 <[email protected]>
- Signed-off-by: Ingo Molnar <[email protected]>
- Closes #20531
- ---
- --- a/arch/x86/kernel/tsc.c
- +++ b/arch/x86/kernel/tsc.c
- @@ -21,6 +21,7 @@
- #include <asm/hypervisor.h>
- #include <asm/nmi.h>
- #include <asm/x86_init.h>
- +#include <asm/geode.h>
-
- unsigned int __read_mostly cpu_khz; /* TSC clocks / usec, not used here */
- EXPORT_SYMBOL(cpu_khz);
- @@ -1004,15 +1005,17 @@ 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;
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