On 2022-10-04, Grant Edwards <grant.b.edwards@xxxxxxxxx> wrote: > I just ran into what I think is the same problem when upgrading from > 5.10.76 to 5.15.68 (sorry I don't have any intermediate kernel > versions to test with). This is an oxford quad 950 board that has > worked flawlessly for many years. Now the baud rates are all wrong. > > [...] After reading through the thread a third time, I tried enabling CONFIG_SERIAL_8250_16550A_VARIANTS in my 6.15.69 kernel, and my quad Oxford board works again. The first two times I read through the thread I misunderstood the statement Can you please confirm that you have the CONFIG_SERIAL_8250_16550A_VARIANTS option disabled (default to "off" for x86 only)? as meaning that you should disable that option as a prerequisite to making it work. So I checked to make sure it was disabled (it was). Yes, it's obvious now what was meant was that having it disabled explains the previous observations. -- Grant