From: Andi Kleen Date: Wed, 30 Jan 2008 12:32:41 +0000 (+0100) Subject: x86: remove explicit C3 TSC check on 64bit X-Git-Tag: v2.6.25-rc1~1143^2~414 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=32c7553f824d0d76771404f0e11d6059f82e8de7;p=linux-2.6 x86: remove explicit C3 TSC check on 64bit Trust the ACPI code to disable TSC instead when C3 is used. AMD Fam10h does not disable TSC in any C states so the check was incorrect there anyways after the change to handle this like Intel on AMD too. This allows to use the TSC when C3 is disabled in software (acpi.max_c_state=2), but the BIOS supports it anyways. Match i386 behaviour. Cc: lenb@kernel.org Signed-off-by: Andi Kleen Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner --- diff --git a/arch/x86/kernel/tsc_64.c b/arch/x86/kernel/tsc_64.c index 322b38c681..c62f3b6eac 100644 --- a/arch/x86/kernel/tsc_64.c +++ b/arch/x86/kernel/tsc_64.c @@ -273,15 +273,8 @@ __cpuinit int unsynchronized_tsc(void) return 1; #endif - if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC)) { -#ifdef CONFIG_ACPI - /* But TSC doesn't tick in C3 so don't use it there */ - if (acpi_gbl_FADT.header.length > 0 && - acpi_gbl_FADT.C3latency < 1000) - return 1; -#endif + if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC)) return 0; - } /* Assume multi socket systems are not synchronized */ return num_present_cpus() > 1;