FM / parameters

/sys/module/libata/parameters

Name	Size	Mode	Actions
acpi_gtf_filter	4096	0644	edit dl rm
allow_tpm	4096	0444	edit dl rm
atapi_an	4096	0444	edit dl rm
atapi_dmadir	4096	0444	edit dl rm
atapi_enabled	4096	0444	edit dl rm
atapi_passthru16	4096	0444	edit dl rm
ata_probe_timeout	4096	0444	edit dl rm
dma	4096	0444	edit dl rm
fua	4096	0444	edit dl rm
ignore_hpa	4096	0644	edit dl rm
noacpi	4096	0444	edit dl rm
zpodd_poweroff_delay	4096	0644	edit dl rm

Edit: /sys/module/libata/parameters/atapi_dmadir (4096B)