u-boot-brain/configs/rpi_3_defconfig
Alexander Graf 601147b06a serial: bcm283x_mu: Detect disabled serial device
On the raspberry pi, you can disable the serial port to gain dynamic frequency
scaling which can get handy at times.

However, in such a configuration the serial controller gets its rx queue filled
up with zero bytes which then happily get transmitted on to whoever calls
getc() today.

This patch adds detection logic for that case by checking whether the RX pin is
mapped to GPIO15 and disables the mini uart if it is not mapped properly.

That way we can leave the driver enabled in the tree and can determine during
runtime whether serial is usable or not, having a single binary that allows for
uart and non-uart operation.

Signed-off-by: Alexander Graf <agraf@suse.de>
Acked-by: Stephen Warren <swarren@wwwdotorg.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
2016-09-06 13:18:19 -04:00

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CONFIG_ARM=y
CONFIG_ARCH_BCM283X=y
CONFIG_TARGET_RPI_3=y
CONFIG_OF_BOARD_SETUP=y
CONFIG_HUSH_PARSER=y
CONFIG_SYS_PROMPT="U-Boot> "
# CONFIG_CMD_IMLS is not set
# CONFIG_CMD_FLASH is not set
CONFIG_CMD_MMC=y
CONFIG_CMD_USB=y
# CONFIG_CMD_FPGA is not set
CONFIG_CMD_GPIO=y
CONFIG_CMD_DHCP=y
CONFIG_CMD_MII=y
CONFIG_CMD_PING=y
CONFIG_CMD_EXT2=y
CONFIG_CMD_EXT4=y
CONFIG_CMD_FAT=y
CONFIG_CMD_FS_GENERIC=y
CONFIG_PHYS_TO_BUS=y
CONFIG_OF_LIBFDT=y
# CONFIG_REQUIRE_SERIAL_CONSOLE is not set
CONFIG_SYS_MALLOC_F_LEN=0x2000