Nico Huber has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/40322 )
Change subject: soc/amd/picasso: Clean up legacy UART config ......................................................................
Patch Set 3:
Haha, turns out I forgot to ask what this is used for? is it for software without a memory-mapped UART driver?
The motive is to provide an option to enable legacy uart on picasso. I don't know when this would be used except for the case where the mmio driver is not available. The PICASSO_UART_LEGACY_RANGE was added because there was a request for more flexibility in the original review. Reviewing this second time, I too am unsure if this flexibility is needed it should probably just be mapped 0:0x3f8, 1:0x2f8, 2:0x3e8, 3:0x2e8. This would match uart8250io.c. Since this isn't even used at the moment, I suggest we skip this patch and I'll take another look at cleaning this up when I have some time.
Thanks. What I'm mostly concerned about now is that this is mixed with console options. UART_FOR_CONSOLE depends on CONSOLE_SERIAL. So if anybody would want any Picasso UART with legacy interface they'd be forced to enable serial console. That seems odd.