google/gru: drive WLAN_MODULE_RST# low as early as possible

GPIO1_B3 (WLAN_MODULE_RST#) defaults as a pull-up input, but it is also
"pulled up" by 1.8V_WLAN. However, 1.8V_WLAN remains low for some time
during early boot. This leaves the signal floating somewhere in the
middle.

This has two potential issues:
(1) we're leaking some power for some (hopefully) short period of time
(2) we are possibly screwing with the Wifi power sequence; we aren't
    supposed to deassert PDn (i.e., MODULE_RST#) until all the rails
    have fully ramped for some period of time

Neither of the above issues are likely to be significant, but it is nice
to fix, I expect.

BRANCH=gru
BUG=chrome-os-partner:54026
TEST=measure WLAN_MODULE_RST# on scope at boot time

Change-Id: Ia6af9ad6954ad8feeda33015e3f205842380939e
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: 0e890a2787bf034d3358a33fc88c2dd8078593ab
Original-Change-Id: I120e26ad0ca486a326874986e142dcaee965b62d
Original-Signed-off-by: Brian Norris <briannorris@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/388009
Original-Reviewed-by: Douglas Anderson <dianders@chromium.org>
Original-Reviewed-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/16882
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Martin Roth <martinroth@google.com>

0 files changed, 0 insertions, 0 deletions