[RESEND][PATCH u-boot v2019.04-aspeed-openbmc v5 2/2] arm/mach-aspeed: Add support for CONFIG_ASPEED_ROUTE_UART5_TO_UART1

[Andrew Jeffery]

Hi Patrick,

On Thu, 30 Jun 2022, at 20:37, Patrick Rudolph wrote:
> Introduce CONFIG_ASPEED_ROUTE_UART5_TO_UART1 and reuse existing
> platform code to route UART5 to UART1.
> This is required on IBM/Genesis3 as it uses UART5 as debug uart, but the
> RXD1/TXD1 pins are connected instead of RXD5/TXD5.

It would be good to clarify the language here. From the patch below
you're re-routing the BMC console from UART5 to UART1 because of a
design issue. However, the ASPEED BMC SoCs have a separate function
known as the "Debug UART" which gives unconstrained access to the BMC's
AHB via either UART5 or UART1. The password sequence is sniffed off of
RXD{1,5} between the IO port and the UART mux, so muxing the UARTs as
you've done isn't enough to enable the feature given the hardware
design.

As such I just want to clarify that you do mean just the console and not
the debug functionality itself. Further, if this is the case, I'm
wondering whether you should enable both the BMC console _and_ the debug
UART function on UART1 (see SCU070[29], though this depends on it being
enabled at all (SCU02C[10]).

Cheers,

Andrew