nyan*: Clear VDDIO_SDMMC3 to reset SD card reader.

When across warm reset, if VDD_3V3_SD_CARD gets power-cycled but VDDIO_SDMMC3
does not, we will get ~1.5V leakage on VDD. To fix that, we reset VDDIO_SDMMC3
to 0 along with VDD_3V3_SD_CARD in Coreboot.  Payloads must turn on VDDIO_SDMMC3
explicitly before accessing SD card.

Note the warnings of "VDD_SDMMC must set early" in comment seems only happens on
U-Boot and can be removed.

BUG=chrome-os-partner:27053
BRNACH=nyan
TEST=Ctrl-U to boot from SD card, login and type "reboot", then Ctrl-U to boot
     again. Without this patch, system will fail in loading kernel.

Original-Change-Id: I7f85995317d18587d514ea3afcff3bfea0a33e93
Original-Signed-off-by: Hung-Te Lin <hungte@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/196961
Original-Reviewed-by: Gabe Black <gabeblack@chromium.org>
Original-Tested-by: Andrew Bresticker <abrestic@chromium.org>
(cherry picked from commit 2cfdb78d9dc229a3c06f19bbe137d59d923908a4)
Signed-off-by: Marc Jones <marc.jones@se-eng.com>

Change-Id: Ie7d814e0424478c35a56fbc959437ee6a555684a
Reviewed-on: http://review.coreboot.org/7866
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

0 files changed, 0 insertions, 0 deletions