From: David Wang <davidwang@zhaoxin.com>
To: <rjw@rjwysocki.net>, <len.brown@intel.com>, <pavel@ucw.cz>,
<tglx@linutronix.de>, <mingo@redhat.com>, <hpa@zytor.com>,
<x86@kernel.org>, <linux-pm@kernel.org>,
<linux-kernel@vger.kernel.org>
Cc: <brucechang@via-alliance.com>, <cooperyan@zhaoxin.com>,
<qiyuanwang@zhaoxin.com>, <benjaminpan@viatech.com>,
<lukelin@viacpu.com>, <timguo@zhaoxin.com>,
<cobechen@zhaoxin.com>, <jiangbowang@zhaoxin.com>,
David Wang <davidwang@zhaoxin.com>
Subject: [PATCH] Delete some unusefull operations for centaur CPU/platform
Date: Fri, 2 Mar 2018 12:11:48 +0800 [thread overview]
Message-ID: <1519963908-4359-1-git-send-email-davidwang@zhaoxin.com> (raw)
For Centaur CPU, the ucode will make sure that each CPU core can keep cache
coherency with each other when the CPU core entering to any C state. So the
cache flush operations when enter C3 is not necessary and will cause large
C3 enter/exit latency.
And the bus master disable operation when CPU core entering C3 state is not
needed too. Because the chipset will automatically do this operation.
Signed-off-by: David Wang <davidwang@zhaoxin.com>
---
arch/x86/kernel/acpi/cstate.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/arch/x86/kernel/acpi/cstate.c b/arch/x86/kernel/acpi/cstate.c
index dde437f..1cd357b 100644
--- a/arch/x86/kernel/acpi/cstate.c
+++ b/arch/x86/kernel/acpi/cstate.c
@@ -51,6 +51,18 @@ void acpi_processor_power_init_bm_check(struct acpi_processor_flags *flags,
if (c->x86_vendor == X86_VENDOR_INTEL &&
(c->x86 > 0xf || (c->x86 == 6 && c->x86_model >= 0x0f)))
flags->bm_control = 0;
+
+ if (c->x86_vendor == X86_VENDOR_CENTAUR) {
+ /*
+ * on all centaur CPUs, sw need not execute cache flush operation
+ * when entering C3 type State.
+ *
+ * On all Centaur platforms, sw need not execute ARB_DISABLE while
+ * entering C3 type state.
+ */
+ flags->bm_check = 1;
+ flags->bm_control = 0;
+ }
}
EXPORT_SYMBOL(acpi_processor_power_init_bm_check);
--
1.9.1
next reply other threads:[~2018-03-02 4:13 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-02 4:11 David Wang [this message]
2018-03-02 11:31 ` [PATCH] Delete some unusefull operations for centaur CPU/platform Rafael J. Wysocki
2018-03-04 9:31 ` Ingo Molnar
[not found] ` <efc93496e4ba46958b7b09eff54c2ce2@zhaoxin.com>
2018-03-12 8:40 ` 答复: " Ingo Molnar
2018-03-12 9:27 ` Rafael J. Wysocki
2018-03-12 9:46 ` Ingo Molnar
[not found] ` <0230c32412474e97bf7d2ef45cc64c4d@zhaoxin.com>
2018-03-29 11:03 ` 答复: " Rafael J. Wysocki
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