libpayload/libc/console: Flush input driver buffer on init

When console input driver registers itself, perform flush of input
buffer to avoid interpreting any stale key presses before libpayload
is run.

keyboard.c: Remove the redundant buffer flush.
8250.c: Ensure that serial_hardware_is_present is set before call to
add input driver.

TEST=Verified that any key presses in serial console before payload is
up do not have any effect after the payload starts running.

Change-Id: I46f1b6715ccf6418f5b2c741bf90db2ece26a60d
Signed-off-by: Furquan Shaikh <>
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <>
3 files changed