Felix Held has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/44529 )
Change subject: mb/amd/mandolin: select ACPI driver for internal memory mapped UARTs ......................................................................
Patch Set 1:
(2 comments)
https://review.coreboot.org/c/coreboot/+/44529/1/src/mainboard/amd/mandolin/... File src/mainboard/amd/mandolin/Kconfig:
https://review.coreboot.org/c/coreboot/+/44529/1/src/mainboard/amd/mandolin/... PS1, Line 13: DRIVERS_UART_ACPI
if !AMD_LPC_DEBUG_CARD
no, that's independent of that setting. AMD_LPC_DEBUG_CARD only says that the LPC UART expansion board is present and should be used for coreboot console. The ACPI UART driver makes it possible for the OS to find and use the MMIO UARTs that aren't disabled in devicetree. Even when using the LPC UART, it still might be useful to still be able to use the integrated UARTs from the OS.
https://review.coreboot.org/c/coreboot/+/44529/1/src/mainboard/amd/mandolin/... PS1, Line 14: PICASSO_CONSOLE_UART
Can Picasso's UARTs work in non-ACPI mode? If not, I'd select DRIVERS_UART_ACPI in PICASSO_CONSOLE_U […]
One of the UARTs can be switched to legacy mode; see CB:40322 If the UARTs are in MMIO mode, there needs to be some entry in the ACPI tables in order for the operating system to find and use it. PICASSO_CONSOLE_UART is independent of UART ACPI mode; the former only affects coreboot and the latter only the OS. PICASSO_CONSOLE_UART doesn't enable the integrated UARTs, but only makes coreboot console use them.