path: root/drivers/acpi
diff options
authordavidwang <davidwang@zhaoxin.com>2018-01-22 18:14:17 +0800
committerThomas Gleixner <tglx@linutronix.de>2018-01-24 13:38:10 +0100
commitfe6daab1ee9dfe7f89974ee6c486cccb0f18a61d (patch)
tree7a8ad4a75e7aa384ae1011ed6abd7d6bd8d502b0 /drivers/acpi
parentaa83c45762a242acce9b35020363225a7b59d7c9 (diff)
x86/centaur: Mark TSC invariant
Centaur CPU has a constant frequency TSC and that TSC does not stop in C-States. But because the corresponding TSC feature flags are not set for that CPU, the TSC is treated as not constant frequency and assumed to stop in C-States, which makes it an unreliable and unusable clock source. Setting those flags tells the kernel that the TSC is usable, so it will select it over HPET. The effect of this is that reading time stamps (from kernel or user space) will be faster and more efficent. Signed-off-by: davidwang <davidwang@zhaoxin.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: qiyuanwang@zhaoxin.com Cc: linux-pm@vger.kernel.org Cc: brucechang@via-alliance.com Cc: cooperyan@zhaoxin.com Cc: benjaminpan@viatech.com Link: https://lkml.kernel.org/r/1516616057-5158-1-git-send-email-davidwang@zhaoxin.com
Diffstat (limited to 'drivers/acpi')
1 files changed, 1 insertions, 0 deletions
diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index d50a7b6ccddd..5f0071c7e2e1 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -207,6 +207,7 @@ static void tsc_check_state(int state)
switch (boot_cpu_data.x86_vendor) {
case X86_VENDOR_AMD:
* AMD Fam10h TSC will tick in all
* C/P/S0/S1 states when this bit is set.

Privacy Policy