[BUG] Kernel disables DMA on RICOH CD-R/RW

[Srihari Vijayaraghavan]

As of 2.6.9-rc4 (I have verified this to be case all
the way up to 2.6.10-rc2), kernel displays this
message:

Uniform Multi-Platform E-IDE driver Revision:
7.00alpha2
ide: Assuming 33MHz system bus speed for PIO modes;
override with idebus=xx
VP_IDE: IDE controller at PCI slot 0000:00:0f.1
ACPI: PCI interrupt 0000:00:0f.1[A] -> GSI 20 (level,
low) -> IRQ 20
VP_IDE: chipset revision 6
VP_IDE: not 100% native mode: will probe irqs later
VP_IDE: VIA vt8237 (rev 00) IDE UDMA133 controller on
pci0000:00:0f.1
    ide0: BM-DMA at 0xcc00-0xcc07, BIOS settings:
hda:DMA, hdb:pio
    ide1: BM-DMA at 0xcc08-0xcc0f, BIOS settings:
hdc:DMA, hdd:DMA
Probing IDE interface ide0...
hda: ST3120026A, ATA DISK drive
Using anticipatory io scheduler
ide0 at 0x1f0-0x1f7,0x3f6 on irq 14
Probing IDE interface ide1...
hdc: Pioneer DVD-ROM ATAPIModel DVD-113 0113, ATAPI
CD/DVD-ROM drive
hdd: RICOH CD-R/RW MP7083A, ATAPI CD/DVD-ROM drive
hdd: Disabling (U)DMA for RICOH CD-R/RW MP7083A
(blacklisted)

The kernel disables DMA on the CD-R/RW (/dev/hdd) and
of course it would not let me enable it manually
either. Up until 2.6.9-rc3 the drive worked in DMA
mode just fine.

(I have been using this drive for more than 4 years. I
have used it under 2.2.x, 2.4.x, >=2.5.50 in DMA mode
just fine. Although I have changed everything else in
the computer in those long years: CPU, M/B, RAM, HDD
etc., save this great CD-R/RW drive, which has been
working fine.)

So the question is: why?
(And what can I do to enable DMA again?)

Thank you.
Hari.

PS: Please cc me on reply, since I am not subscribed
to LKML.


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