cros_ec_softrec_power: Disable flushing to issue "reboot ap-off"

For the legacy devices without the EC reboot option "wait-ext". It
issues a command "reboot ap-off" immediately after a cold reset.
So it can clear the EC_IN_RW latch and ensure AP off.

Found that on servo v3, the "reboot ap-off" takes several seconds
to be executed as it has to flush all incoming messages. This delay
causes issues, like double recovery boot. We should disable flushing.

BUG=b:134968779
TEST=Added a param wait_ext_is_fake="yes" to the octopus overlay
to emualte the legacy devices.

Executed the command "dut-control power_state:rec" and verified
the "reboot ap-off" is issued almost instantly after cold reset.

Change-Id: Iab537b9c3891d20987d7a4688a7f205db1da01ab
Reviewed-on: https://chromium-review.googlesource.com/1651499
Commit-Ready: Wai-Hong Tam <waihong@google.com>
Tested-by: Wai-Hong Tam <waihong@google.com>
Legacy-Commit-Queue: Commit Bot <commit-bot@chromium.org>
Reviewed-by: Nick Sanders <nsanders@chromium.org>
1 file changed