commit 7f287d23bc05606a805a61bc193d2a78c388f620
author Tim Wawrzynczak <twawrzynczak@chromium.org> Thu Sep 01 11:48:38 2022 -0600
committer Felix Held <felix-coreboot@felixheld.de> Mon Sep 12 12:31:24 2022 +0000
tree e6d967474757cd7642b5a82c5ee26a8facc5312b
parent d6ac209c74a2ce8d0d7f07390f62d447c02fedf3

mb/google/brya/acpi: Move dGPU power checks earlier

Linux always "turns on" a PowerResource when it boots, regardless of
_STA, so the _ON routine should be idempotent. In this case, it all is,
except for the LTR restore, which would restore a value of 0 when _ON is
run the first time, which means that LTR is disabled on the root port
from then on, as the save/restore routines will keep saving/restoring
that 0. THis patch fixes the problem by moving the power checks from
PGON/PGOF to GCOO/GCOI.

BUG=b:244409563
TEST=boot agah and verify that LTR is still enabled on the root port

Signed-off-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Change-Id: I4ed78323608eede5b8310598f1f1115497ab2b5b
Reviewed-on: https://review.coreboot.org/c/coreboot/+/67278
Reviewed-by: Cliff Huang <cliff.huang@intel.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Tarun Tuli <taruntuli@google.com>

src/mainboard/google/brya/acpi/power.asl

diff --git a/src/mainboard/google/brya/acpi/power.asl b/src/mainboard/google/brya/acpi/power.asl
index 2654394..a384297 100644
--- a/src/mainboard/google/brya/acpi/power.asl
+++ b/src/mainboard/google/brya/acpi/power.asl
@@ -182,12 +182,6 @@
 /* GCOFF exit sequence */
 Method (PGON, 0, Serialized)
 {
-	If (GPPS == GPU_POWER_STATE_ON)
-	{
-		Printf ("PGON: GPU already on")
-		Return
-	}
-
 	Local0 = Timer - GCOT
 	If (Local0 < MIN_OFF_TIME_TIMERS)
 	{
@@ -234,12 +228,6 @@
 /* GCOFF entry sequence */
 Method (PGOF, 0, Serialized)
 {
-	If (GPPS == GPU_POWER_STATE_OFF)
-	{
-		Printf ("GPU already off")
-		Return
-	}
-
 	/* Assert PERST# */
 	CTXS (GPIO_GPU_PERST_L)
 
@@ -278,6 +266,12 @@
 /* GCOFF Out, i.e. full power-on sequence */
 Method (GCOO, 0, Serialized)
 {
+	If (GPPS == GPU_POWER_STATE_ON)
+	{
+		Printf ("PGON: GPU already on")
+		Return
+	}
+
 	SRCC (SRCCLK_ENABLE)
 	PGON ()
 	\_SB.PCI0.PEG0.LD23 ()
@@ -310,9 +304,14 @@
 /* GCOFF In, i.e. full power-off sequence */
 Method (GCOI, 0, Serialized)
 {
+	If (GPPS == GPU_POWER_STATE_OFF)
+	{
+		Printf ("GPU already off")
+		Return
+	}
+
 	/* Save the PEG port's LTR setting */
 	SLTR = LREN
-
 	\_SB.PCI0.PEG0.DL23 ()
 	PGOF ()
 	SRCC (SRCCLK_DISABLE)