When booting Linux as a coreboot payload, serial access does not work
properly. This is because the setup code erroneously sets IRQ3 and
IRQ4 to level. The UART on Broadwell is 8250/16550 compatible, thus
ISA and edge-triggered.
This change is not necessary on the non-FSP version of Broadwell support.
The non-FSP version does not set these IRQ overrides.
Fix verified booting Linux 4.6.0-rc2 on Intel Camelback Mountain CRB,
using Intel FSP 1.0.
Change-Id: I17b466676e7f4891c3e75ce6208e1580c9eaf742
Signed-off-by: Kevin Paul Herbert <kevin@trippers.org>
Reviewed-on: https://review.coreboot.org/16065
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
d7127b09ae