CVE-2026-98883

In the Linux kernel, the following vulnerability has been resolved:

serial: 8250 port: recognize UPIO AU

My MIPS Alchemy systems generate the following warning during probe of the 8250 driver:

WARNING: drivers/tty/serial/8250/8250 port.c:462 at set io from upio+0xfc/0x124, CPU#0: swapper/0/1 Unsupported UART type 4 [...] [<80521d40>] set io from upio+0xfc/0x124 [<80521dfc>] serial8250 set defaults+0x94/0xe0 [<80520fb4>] serial8250 register 8250 port+0x288/0x51c [<805214ec>] serial8250 probe+0x160/0x1e8 [<8053b5f0>] platform probe+0x64/0x90

The least invasive fix is to recognize UPIO AU (type 4) in set io from upio() and do nothing, since all parameters have already been set up in 8250 rt288x.c::au platform setup().

Run-tested on Alchemy Au1300 platform.