From 6ff848aaf811789460f7bf6f0f89f71aa7fe8bee Mon Sep 17 00:00:00 2001 From: Duncan Laurie Date: Thu, 13 Jun 2019 11:07:04 -0700 Subject: [PATCH] ec/google/wilco: Read back from EC RAM after S0ix entry We are seeing an EC interrupt after setting the EC RAM offset that indicates that the EC should transition to S0ix mode and this is preventing the kernel from going into S0ix on the first try. As a workaround if we read back from the EC RAM while still in the _DSM handler it seems to prevent this problem. BUG=b:130644677 BRANCH=sarien TEST=ensure s0ix entry works on the first try with sarien Change-Id: Id607c4c2b14b79d0cd1bcea0c2032be2f2c0c141 Signed-off-by: Duncan Laurie Reviewed-on: https://review.coreboot.org/c/coreboot/+/33455 Reviewed-by: Shaunak Saha Reviewed-by: Furquan Shaikh Tested-by: build bot (Jenkins) --- src/ec/google/wilco/acpi/ec.asl | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/src/ec/google/wilco/acpi/ec.asl b/src/ec/google/wilco/acpi/ec.asl index 4fa887b1b4..532f421780 100644 --- a/src/ec/google/wilco/acpi/ec.asl +++ b/src/ec/google/wilco/acpi/ec.asl @@ -154,6 +154,12 @@ Device (EC0) If (Arg0) { Printf ("EC Enter S0ix") W (CSEX, One) + + /* + * Read back from EC RAM after enabling S0ix + * to prevent EC from aborting S0ix entry. + */ + R (EVT1) } Else { Printf ("EC Exit S0ix") W (CSEX, Zero)