diff --git a/k/atapi.c b/k/atapi.c
index 3d03630..d03e709 100644
--- a/k/atapi.c
+++ b/k/atapi.c
@@ -24,7 +24,7 @@ static void wait_device_selection(uint16_t drive)
         inb(drive);
 }
 
-static uint8_t is_atapi_driver(uint16_t bus, uint8_t slave)
+static uint8_t is_atapi_drive(uint16_t bus, uint8_t slave)
 {
     static uint8_t atapi_sig[] = { ATAPI_SIG_SC, ATAPI_SIG_LBA_LO,
                                    ATAPI_SIG_LBA_MI, ATAPI_SIG_LBA_HI };
@@ -61,15 +61,31 @@ static uint8_t is_atapi_driver(uint16_t bus, uint8_t slave)
 
 void discover_atapi_drive(void)
 {
-    // primary_reg
+    /* primary_reg */
     outb(PRIMARY_DCR, SRST);
     outb(PRIMARY_DCR, INTERRUPT_DISABLE);
 
+    // master_port
     select_drive(PRIMARY_REG, ATA_PORT_MASTER);
     wait_device_selection(PRIMARY_REG);
-    is_atapi_driver(PRIMARY_REG, ATA_PORT_MASTER);
+    is_atapi_drive(PRIMARY_REG, ATA_PORT_MASTER);
 
-    // secondary_reg
+    // slave port
+    select_drive(PRIMARY_REG, ATA_PORT_SLAVE);
+    wait_device_selection(PRIMARY_REG);
+    is_atapi_drive(PRIMARY_REG, ATA_PORT_SLAVE);
+
+    /* secondary_reg */
     outb(SECONDARY_DCR, SRST);
     outb(SECONDARY_DCR, INTERRUPT_DISABLE);
+
+    // master_port
+    select_drive(SECONDARY_REG, ATA_PORT_MASTER);
+    wait_device_selection(SECONDARY_REG);
+    is_atapi_drive(SECONDARY_REG, ATA_PORT_MASTER);
+
+    // slave port
+    select_drive(SECONDARY_REG, ATA_PORT_SLAVE);
+    wait_device_selection(SECONDARY_REG);
+    is_atapi_drive(SECONDARY_REG, ATA_PORT_SLAVE);
 }