lynxpoint: XHCI: Advertise D3 as lowest wake state

The recommended value in docs is D2, but lynxpoint XHCI does not even
support D2 state which causes the kernel to think this device cannot
be used as a wake source:

kernel: xhci_hcd 0000:00:14.0: System wakeup enabled by ACPI
kernel: ACPI: Device does not support D2
kernel: xhci_hcd 0000:00:14.0: System wakeup disabled by ACPI

Additionally this means the kernel will never put the device into D3
state by itself.  There is SMI code that will put the device into D3
before suspend so advertising D3 here should be correct.

With this change the kernel will put the controller into D3 on suspend
and back to D0 on resume, including executing the ACPI methods
for _PS0/_PS3 that contain chipset specific workarounds.

In addition add a _PSC method to directly return the D state from the
device registers.  With ALL USB devices removed the XHCI controller
goes into D3 state and the kernel can have a hard time determining
the state of the device at boot.

A kernel compiled with CONFIG_ACPI_DEBUG=y and module parameters
acpi.debug_layer=0x7f acpi.debug_level=0x2f can be used to see
what ACPI methods are executed:

kernel: xhci_hcd 0000:00:14.0: System wakeup enabled by ACPI
kernel: ACPI: Execute Method [\_SB_.PCI0.XHCI._PS3] (Node ffff8801000a7f50)
kernel: ACPI: Preparing to enter system sleep state S3
...
kernel: ACPI: Waking up from system sleep state S3
kernel: ACPI: Execute Method [\_SB_.PCI0.XHCI._PS0] (Node ffff8801000a7f28)
kernel: xhci_hcd 0000:00:14.0: power state changed by ACPI to D0

Change-Id: Ic64040eb4dd1947a1e2f0ee253a64be683e0ec70
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>

meld with s3d

Change-Id: Ic6789720c4efe661dcb03a4afce8d88115854472
Reviewed-on: https://gerrit.chromium.org/gerrit/63916
Tested-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Commit-Queue: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: http://review.coreboot.org/4409
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>

1 files changed, 7 insertions, 2 deletions

diff --git a/src/southbridge/intel/lynxpoint/acpi/usb.asl b/src/southbridge/intel/lynxpoint/acpi/usb.asl
index 1a0ad34776..c22dbb80bc 100644
--- a/src/southbridge/intel/lynxpoint/acpi/usb.asl
+++ b/src/southbridge/intel/lynxpoint/acpi/usb.asl
@@ -238,6 +238,11 @@ Device (XHCI)
 		LPCL ()
 	}
 
+	Method (_PSC, 0, NotSerialized)
+	{
+		Return (^D0D3)
+	}
+
 	Method (_PS0, 0, Serialized)
 	{
 		If (LEqual (^DVID, 0xFFFF)) {
@@ -375,12 +380,12 @@ Device (XHCI)
 
 	Method(_S3D,0)	// Highest D State in S3 State
 	{
-		Return (2)
+		Return (3)
 	}
 
 	Method(_S4D,0)	// Highest D State in S4 State
 	{
-		Return (2)
+		Return (3)
 	}
 
 	Device (HUB7)