35f2f8b802
While there is no publicly available schematic of this board, it's not hard to determine voltage of GPIO port C, D and G (only ones which can be set). Port C and G are used for MMC/SDIO communication, so they use 1.8 V power supply. It's not clear if port D is even used, but if it is, it's pretty safe to assume it uses 3.3 V power supply. Value read from PIO Group Withstand Voltage Mode Select register from within pre-installed Android agrees with that assesment. Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com> Signed-off-by: Maxime Ripard <maxime@cerno.tech> Link: https://lore.kernel.org/r/20210722161220.51181-3-jernej.skrabec@gmail.com