I can confirm that there is no such setting in the BIOS.
Node 0x11 [Pin Complex] wcaps 0x400300: Mono Digital Control: name="HDMI Phantom Jack", index=0, device=0 Pincap 0x00000010: OUT Pin Default 0x18567530: [Jack] Digital Out at Int HDMI Conn = Digital, Color = Yellow DefAssociation = 0x3, Sequence = 0x0 Misc = NO_PRESENCE Pin-ctls: 0x40: OUT Connection: 1 0x10
Node 0x1e [Pin Complex] wcaps 0x400300: Mono Digital Control: name="SPDIF Phantom Jack", index=0, device=0 Pincap 0x00000010: OUT Pin Default 0x01441520: [Jack] SPDIF Out at Ext Rear Conn = RCA, Color = Black DefAssociation = 0x2, Sequence = 0x0 Misc = NO_PRESENCE Pin-ctls: 0x40: OUT Connection: 1 0x06
The easy workaround is use hdajackretask change the internal spdif connector node 0x11 as not connected if you only use spdif out at rear panel node 0x1e
Otherwise , you need to sort autocfg.dig_out_pins by def assoc or location so the pin with spdif out at ext instead of the internal spdif connector digitak out at Int is first digital pin
https://git.kernel.org/cgit/linux/kernel/git/tiwai/sound.git/tree/sound/pci/...