Change in coreboot[master]: mb/google/dedede/var/boten: Set the xHCI LFPS period sampling off tim...

[Patrick Georgi (Code Review)]

Patrick Georgi has submitted this change. ( https://review.coreboot.org/c/coreboot/+/56689 )

Change subject: mb/google/dedede/var/boten: Set the xHCI LFPS period sampling off time to 0ms
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mb/google/dedede/var/boten: Set the xHCI LFPS period sampling off time to 0ms

LTE module L850-GL may encounter U3 wakeup race condition with the host.
Setting xHCI LFPS periodic sampling off time to 0ms so that the host would not
miss the device-initiated U3 wakeup thus avoid the race condition.

BUG=b:187801363
BRANCH=dedede
TEST=flash the image to the device. Run following command to check the bits[7:4] is 0x0:
iotools mmio_read32 "XHCI MMIO BAR + 0x80A4"

Signed-off-by: stanley.wu 
Change-Id: I9328e758ed92389e44b25ff4daf6ec19b37ae7d6
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56689
Tested-by: build bot (Jenkins) 
Reviewed-by: Karthik Ramasubramanian 
Reviewed-by: Ben Kao 
---
M src/mainboard/google/dedede/variants/boten/overridetree.cb
1 file changed, 3 insertions(+), 0 deletions(-)

Approvals:
  build bot (Jenkins): Verified
  Karthik Ramasubramanian: Looks good to me, approved
  Ben Kao: Looks good to me, but someone else must approve

diff --git a/src/mainboard/google/dedede/variants/boten/overridetree.cb b/src/mainboard/google/dedede/variants/boten/overridetree.cb
index 8c68f7e..d310f91 100644
--- a/src/mainboard/google/dedede/variants/boten/overridetree.cb
+++ b/src/mainboard/google/dedede/variants/boten/overridetree.cb
@@ -80,6 +80,9 @@
    register "SlowSlewRate" = "SlewRateFastBy8"
    register "FastPkgCRampDisable" = "1"

+	# Set xHCI LFPS period sampling off time to 0 ms
+	register "xhci_lfps_sampling_offtime_ms" = "0"
+
    device domain 0 on
    	device pci 04.0 on
    		chip drivers/intel/dptf