掲題の通り、BIOSでAHCIを選択するとDVDが認識しないです。
BIOS設定をAHCIのまま認識させる方法について、お知恵を貸していただけないでしょうか？

AHCIの場合、ブート時のDVDドライブテストがfailedとなっております。

＊＊＊BIOSでAHCIを選択した場合のdmseg＊＊＊
$dmesg | grep ata2
[    1.452777] ata2: SATA max UDMA/133 abar m2048@0xd0200000 port 0xd0200180 irq 26
[    2.004059] ata2: SATA link up 1.5 Gbps (SStatus 113 SControl 300)
[    2.004777] ata2.00: ATAPI: Optiarc DVD+/-RW AD-5540A, 102C, max UDMA/33
[    2.004780] ata2.00: applying bridge limits
[    2.005728] ata2.00: configured for UDMA/33 (device error ignored)
[    7.136028] ata2.00: qc timeout (cmd 0xa0)
[    7.136034] ata2.00: TEST_UNIT_READY failed (err_mask=0x4)
[    7.688027] ata2: SATA link up 1.5 Gbps (SStatus 113 SControl 300)
[    7.689690] ata2.00: configured for UDMA/33 (device error ignored)
[   12.768018] ata2.00: qc timeout (cmd 0xa0)
[   12.768023] ata2.00: TEST_UNIT_READY failed (err_mask=0x4)
[   12.768025] ata2: limiting SATA link speed to 1.5 Gbps
[   12.768027] ata2.00: limiting speed to UDMA/33:PIO3
[   13.320026] ata2: SATA link up 1.5 Gbps (SStatus 113 SControl 310)
[   13.321684] ata2.00: configured for UDMA/33 (device error ignored)
[   18.400020] ata2.00: qc timeout (cmd 0xa0)
[   18.400025] ata2.00: TEST_UNIT_READY failed (err_mask=0x4)
[   18.400026] ata2.00: disabled
[   18.400035] ata2: hard resetting link
[   18.952026] ata2: SATA link up 1.5 Gbps (SStatus 113 SControl 310)
[   18.952031] ata2: EH complete

$dmesg | grep scsi
[    1.452125] scsi host0: ahci
[    1.452276] scsi host1: ahci
[    1.452385] scsi host2: ahci
[    1.452495] scsi host3: ahci
[    1.452606] scsi host4: ahci
[    1.452712] scsi host5: ahci
[    1.459130] scsi host6: ahci
[    1.464090] scsi host7: ahci
[    1.768447] scsi 0:0:0:0: Direct-Access     ATA      ST2000DL003-9VT1 CC32 PQ: 0 ANSI: 5
[    1.776956] scsi host8: usb-storage 1-3:1.0
[    1.800262] sd 0:0:0:0: Attached scsi generic sg0 type 0
[    2.784717] scsi 8:0:0:0: Direct-Access     SanDisk  Ultra Fit        1.00 PQ: 0 ANSI: 6
[    2.785130] sd 8:0:0:0: Attached scsi generic sg1 type 0
[   18.952285] scsi 6:0:0:0: Direct-Access     ATA      DOGFISH 120G     4B0  PQ: 0 ANSI: 5
[   18.988281] sd 6:0:0:0: Attached scsi generic sg2 type 0



BIOS設定がATAの場合、ブート時にATAデバイスをSCSIデバイスとしてエミュレートしてDVDやHDDを認識している模様。
しかし何故かSSDだけは、[    2.345119] scsi host5: ahciとなっており、AHCIが有効になっているみたいです。

＊＊＊BIOSでATAを選択した場合のdmseg＊＊＊
$dmesg | grep ata2
[    1.392708] ata2: SATA max UDMA/133 cmd 0xfe20 ctl 0xfe30 bmdma 0xfec8 irq 20
[    2.176229] ata2.00: SATA link up 1.5 Gbps (SStatus 113 SControl 300)
[    2.176239] ata2.01: SATA link down (SStatus 0 SControl 300)
[    2.176248] ata2.01: link offline, clearing class 3 to NONE
[    2.178637] ata2.00: ATAPI: Optiarc DVD+/-RW AD-5540A, 102C, max UDMA/33
[    2.178639] ata2.00: applying bridge limits
[    2.183312] ata2.00: configured for UDMA/33

$dmesg | grep scsi
[    1.392462] scsi host0: ata_piix
[    1.392627] scsi host1: ata_piix
[    1.552352] scsi host2: ata_piix
[    1.552512] scsi host3: ata_piix
[    2.183834] scsi 0:0:0:0: Direct-Access     ATA      ST2000DL003-9VT1 CC32 PQ: 0 ANSI: 5
[    2.212246] sd 0:0:0:0: Attached scsi generic sg0 type 0
[    2.213331] scsi 1:0:0:0: CD-ROM            Optiarc  DVD+-RW AD-5540A 102C PQ: 0 ANSI: 5
[    2.225196] sr 1:0:0:0: [sr0] scsi3-mmc drive: 24x/24x writer cd/rw xa/form2 cdda tray
[    2.225386] sr 1:0:0:0: Attached scsi CD-ROM sr0
[    2.225467] sr 1:0:0:0: Attached scsi generic sg1 type 5
[    2.337790] scsi host4: usb-storage 1-3:1.0
[    2.345119] scsi host5: ahci
[    2.347144] scsi host6: ahci
[    2.843597] scsi 5:0:0:0: Direct-Access     ATA      DOGFISH 120G     4B0  PQ: 0 ANSI: 5
[    2.896341] sd 5:0:0:0: Attached scsi generic sg2 type 0
[    3.356671] scsi 4:0:0:0: Direct-Access     SanDisk  Ultra Fit        1.00 PQ: 0 ANSI: 6
[    3.357120] sd 4:0:0:0: Attached scsi generic sg3 type 0