--- a/sys/dev/disk/nata/chipsets/ata-cyrix.c	2026-10-20 22:34:43.683425774 +0000
+++ b/sys/dev/disk/nata/chipsets/ata-cyrix.c	2026-10-20 22:34:52.011318628 +0000
@@ -95,7 +95,7 @@
 	    }
 	    else {
 		ATA_OUTL(ch->r_io[ATA_BMCMD_PORT].res,
-			 0x20 + (devno << 3), piotiming[mode & ATA_MODE_MASK]);
+			 0x20 + (devno << 3), piotiming[ata_mode2idx(mode)]);
 	    }
 	}
 	atadev->mode = mode;