linux-kernel - [19/55] intel_idle: disable Atom/Lincroft HW C-state auto-demotion

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Date:	Fri, 25 Mar 2011 16:47:12 -0700
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Len Brown <len.brown@...el.com>
Subject: [19/55] intel_idle: disable Atom/Lincroft HW C-state auto-demotion

2.6.37-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Len Brown <len.brown@...el.com>

commit bfb53ccf1c734b1907df7189eef4c08489827951 upstream.

Just as we had to disable auto-demotion for NHM/WSM,
we need to do the same for Atom (Lincroft version).

In particular, auto-demotion will prevent Lincroft
from entering the S0i3 idle power saving state.

https://bugzilla.kernel.org/show_bug.cgi?id=25252

Signed-off-by: Len Brown <len.brown@...el.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 arch/x86/include/asm/msr-index.h |    1 +
 drivers/idle/intel_idle.c        |    4 ++++
 2 files changed, 5 insertions(+)

--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -39,6 +39,7 @@
 #define MSR_NHM_SNB_PKG_CST_CFG_CTL	0x000000e2
 #define NHM_C3_AUTO_DEMOTE		(1UL << 25)
 #define NHM_C1_AUTO_DEMOTE		(1UL << 26)
+#define ATM_LNC_C6_AUTO_DEMOTE		(1UL << 25)
 
 #define MSR_MTRRcap			0x000000fe
 #define MSR_IA32_BBL_CR_CTL		0x00000119
--- a/drivers/idle/intel_idle.c
+++ b/drivers/idle/intel_idle.c
@@ -340,8 +340,12 @@ static int intel_idle_probe(void)
 		break;
 
 	case 0x1C:	/* 28 - Atom Processor */
+		cpuidle_state_table = atom_cstates;
+		break;
+
 	case 0x26:	/* 38 - Lincroft Atom Processor */
 		cpuidle_state_table = atom_cstates;
+		auto_demotion_disable_flags = ATM_LNC_C6_AUTO_DEMOTE;
 		break;
 
 	case 0x2A:	/* SNB */


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