FM / ata4

/sys/devices/pci0000:00/0000:00:1f.2/ata4/ata_port/ata4

Name	Size	Mode	Actions
device/	-	0755	rm
power/	-	0755	rm
subsystem/	-	0755	rm
idle_irq	4096	0444	edit dl rm
nr_pmp_links	4096	0444	edit dl rm
port_no	4096	0444	edit dl rm
uevent	4096	0644	edit dl rm

Edit: /sys/devices/pci0000:00/0000:00:1f.2/ata4/ata_port/ata4/port_no (4096B)