Patch set updated for coreboot: fe487f6 Persimmon DSDT: Add OSC method

[Mike Loptien]

Mike Loptien ([e-mail]) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/2684

-gerrit

commit fe487f638d781307de91c21178d96634407f669e
Author: Mike Loptien 
Date:   Tue Mar 12 10:21:24 2013 -0600

Persimmon DSDT: Add OSC method

The _OSC method is used to tell the OS what capabilities
    it can take control over from the firmware.  This method
    is described in chapter 6.2.9 of the ACPI spec v3.0.
    The method takes 4 inputs (UUID, Rev ID, Input Count,
    and Capabilities Buffer) and returns a Capabilites
    Buffer the same size as the input Buffer.  This Buffer
    is generally 3 Dwords long consisting of an Errors
    Dword, a Supported Capabilities Dword, and a Control
    Dword.  The OS will request control of certain
    capabilities and the firmware must grant or deny control
    of those features.  We do not want to have control over
    anything so let the OS control as much as it can.

The _OSC method is required for PCIe devices and dmesg
    checks for its existence and issues an error if it is
    not found.  Before this change, dmesg gave this message:

pci0000:00: Requesting ACPI _OSC control (0x1d)
    pci0000:00: ACPI _OSC request failed (AE_NOT_FOUND), returned control mask: 0x1d
    ACPI _OSC control for PCIe not granted, disabling ASPM

After this change, dmesg looks like this:

pci0000:00: Requesting ACPI _OSC control (0x1d)
    pci0000:00: ACPI _OSC control (0x1d) granted

Change-Id: I1494285def7440972f0549b7cb73eb94dafc72c2
    Signed-off-by: Mike Loptien 
---
 src/mainboard/amd/persimmon/dsdt.asl | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/src/mainboard/amd/persimmon/dsdt.asl b/src/mainboard/amd/persimmon/dsdt.asl
index 148d7b0..d29bbff 100644
--- a/src/mainboard/amd/persimmon/dsdt.asl
+++ b/src/mainboard/amd/persimmon/dsdt.asl
@@ -1157,8 +1157,20 @@ DefinitionBlock (
    	Device(PCI0) {
    		External (TOM1)
    		External (TOM2)
-			Name(_HID, EISAID("PNP0A03"))
+			Name(_HID, EISAID("PNP0A08"))	/* PCI Express Root Bridge */
+			Name(_CID, EISAID("PNP0A03"))	/* PCI Root Bridge */
    		Name(_ADR, 0x00180000)	/* Dev# = BSP Dev#, Func# = 0 */
+
+			/* Operating System Capabilities Method */
+			Method(_OSC, 4)
+			{	/* Check for proper PCI/PCIe UUID */
+				If(LEqual(Arg0,ToUUID("33DB4D5B-1FF7-401C-9657-7441C03DD766")))
+				{
+					/* Let OS control everything */
+					Return (Arg3)
+				}
+			}
+
    		Method(_BBN, 0) { /* Bus number = 0 */
    			Return(0)
    		}