New patch to review for coreboot: 4c11d71 CTDP: Only do TDP down/nominal change from TNP0

[Stefan Reinauer]

Stefan Reinauer ([e-mail]) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/1348

-gerrit

commit 4c11d714adf9a09677a358bea44e86f753b3d45f
Author: Duncan Laurie 
Date:   Wed Jul 18 15:33:45 2012 -0700

CTDP: Only do TDP down/nominal change from TNP0

Otherwise there is a flurry of TDP changes with suspend/resume
    as the kernel powers devices off on suspend and brings them
    back online in resume.

This also adds a mutex around the TDP operations since it is
    split across two methods and can't just rely on being Serialized.

Change-Id: I7757d3ddad34ac985a9c8ce2fc202e2b2dcb2527
    Signed-off-by: Duncan Laurie 
---
 .../intel/sandybridge/acpi/hostbridge.asl          |   30 ++++++++++++++++----
 1 files changed, 24 insertions(+), 6 deletions(-)

diff --git a/src/northbridge/intel/sandybridge/acpi/hostbridge.asl b/src/northbridge/intel/sandybridge/acpi/hostbridge.asl
index 8dd1de6..93db98d 100644
--- a/src/northbridge/intel/sandybridge/acpi/hostbridge.asl
+++ b/src/northbridge/intel/sandybridge/acpi/hostbridge.asl
@@ -101,6 +101,8 @@ Device (MCHC)
    	TLUD,	 32,
    }

+	Mutex (CTCM, 1)		/* CTDP Switch Mutex (sync level 1) */
+	Name (CTCC, 0)		/* CTDP Current Selection */
    Name (CTCN, 0)		/* CTDP Nominal Select */
    Name (CTCD, 1)		/* CTDP Down Select */
    Name (CTCU, 2)		/* CTDP Up Select */
@@ -167,12 +169,16 @@ Device (MCHC)
    /* Set TDP Down */
    Method (STND, 0, Serialized)
    {
-		Store ("Set TDP Down", Debug)
-
-		If (LEqual (CTCD, CTCS)) {
+		If (Acquire (CTCM, 100)) {
+			Return (0)
+		}
+		If (LEqual (CTCD, CTCC)) {
+			Release (CTCM)
    		Return (0)
    	}

+		Store ("Set TDP Down", Debug)
+
    	/* Set CTC */
    	Store (CTCD, CTCS)

@@ -189,18 +195,26 @@ Device (MCHC)
    	/* Set PL1 */
    	Store (CTDD, PL1V)

+		/* Store the new TDP Down setting */
+		Store (CTCD, CTCC)
+
+		Release (CTCM)
    	Return (1)
    }

/* Set TDP Nominal from Down */
    Method (STDN, 0, Serialized)
    {
-		Store ("Set TDP Nominal", Debug)
-
-		If (LEqual (CTCN, CTCS)) {
+		If (Acquire (CTCM, 100)) {
+			Return (0)
+		}
+		If (LEqual (CTCN, CTCC)) {
+			Release (CTCM)
    		Return (0)
    	}

+		Store ("Set TDP Nominal", Debug)
+
    	/* Set PL1 */
    	Store (CTDN, PL1V)

@@ -217,6 +231,10 @@ Device (MCHC)
    	/* Set CTC */
    	Store (CTCN, CTCS)

+		/* Store the new TDP Nominal setting */
+		Store (CTCN, CTCC)
+
+		Release (CTCM)
    	Return (1)
    }
 }