[coreboot-gerrit] Change in coreboot[master]: nocturne: disable p-states

[Nick Vaccaro (Code Review)]

Nick Vaccaro has uploaded this change for review. ( https://review.coreboot.org/27156

Change subject: nocturne: disable p-states
......................................................................

nocturne: disable p-states

Add "intel_pstate=no_hwp" to the kernel command line to instruct
kernel to disable p-states as a temporary workaround for an SoC
hang.

BUG=b:79666828
BRANCH=none
TEST="emerge-nocturne depthcharge coreboot chromeos-bootimage",
flash spi image onto nocturne, boot to kernel and verify device
stays alive and responsive for several minutes without locking up.

Change-Id: I71ed4c80c109b28ffa85d48338ce3a62396d272e
Signed-off-by: Nick Vaccaro 
---
M src/mainboard/google/poppy/variants/nocturne/devicetree.cb
1 file changed, 2 insertions(+), 1 deletion(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/56/27156/1

diff --git a/src/mainboard/google/poppy/variants/nocturne/devicetree.cb b/src/mainboard/google/poppy/variants/nocturne/devicetree.cb
index f746c08..0b30caa 100644
--- a/src/mainboard/google/poppy/variants/nocturne/devicetree.cb
+++ b/src/mainboard/google/poppy/variants/nocturne/devicetree.cb
@@ -60,7 +60,8 @@
    register "PmTimerDisabled" = "1"
    register "VmxEnable" = "1"

-	register "speed_shift_enable" = "1"
+	# Disable P-States
+	register "speed_shift_enable" = "0"
    register "dptf_enable" = "1"
    register "tdp_pl2_override" = "15"
    register "psys_pmax" = "45"