IDE HD DMA not being enabled in 2.4.0

[Josh Straub]

Hello, this is my first post to Linux-Kernel so I hope I get this right.

On my Pentium 200 system with Intel i430VX chipset and PIIX3, my Maxtor
3.5GB IDE HD would always have DMA enabled even in 2.4.0-test10, but then
sometime between 2.4.0-test12 and 2.4.0 (final), DMA was not being enabled
anymore upon boot.

Here is my relevant "dmesg" from 2.4.0-test10:

Uniform Multi-Platform E-IDE driver Revision: 6.31
ide: Assuming 33MHz system bus speed for PIO modes; override with
idebus=xx
PIIX3: IDE controller on PCI bus 00 dev 39
PIIX3: chipset revision 0
PIIX3: not 100% native mode: will probe irqs later
    ide0: BM-DMA at 0xf000-0xf007, BIOS settings: hda:pio, hdb:pio
    ide1: BM-DMA at 0xf008-0xf00f, BIOS settings: hdc:pio, hdd:pio
hda: Maxtor 83500A4, ATA DISK drive
hdb: ST31220A, ATA DISK drive
hdc: ATAPI CDROM, ATAPI CDROM drive
ide0 at 0x1f0-0x1f7,0x3f6 on irq 14
ide1 at 0x170-0x177,0x376 on irq 15
hda: 6839440 sectors (3502 MB) w/256KiB Cache, CHS=848/128/63, (U)DMA
hdb: 2116296 sectors (1084 MB) w/256KiB Cache, CHS=524/64/63, DMA

Notice the drive being picked up as (U)DMA, and the Seagate 1.2GB being
picked up as DMA.

Now look at my 2.4.0 dmesg:

Uniform Multi-Platform E-IDE driver Revision: 6.31
ide: Assuming 33MHz system bus speed for PIO modes; override with
idebus=xx
PIIX3: IDE controller on PCI bus 00 dev 39
PIIX3: chipset revision 0
PIIX3: not 100% native mode: will probe irqs later
    ide0: BM-DMA at 0xf000-0xf007, BIOS settings: hda:pio, hdb:pio
    ide1: BM-DMA at 0xf008-0xf00f, BIOS settings: hdc:pio, hdd:pio
hda: Maxtor 83500A4, ATA DISK drive
hdb: ST31220A, ATA DISK drive
hdc: ATAPI CDROM, ATAPI CDROM drive
ide0 at 0x1f0-0x1f7,0x3f6 on irq 14
ide1 at 0x170-0x177,0x376 on irq 15
hda: 6839440 sectors (3502 MB) w/256KiB Cache, CHS=848/128/63
hdb: 2116296 sectors (1084 MB) w/256KiB Cache, CHS=524/64/63, DMA

Here you can see that DMA is still configured, because the Seagate retains
DMA.  But for some reason the Maxtor is now getting no DMA at all.  I can
use "hdparm" to enable it manually and I did an "updatedb" to generate some
heavy test disk activity, and it worked fine.  So I cannot assume that DMA
is being disabled on my Maxtor on purpose, because of some bad hardware or
something, and I am guessing something changed in the IDE driver recently
that buggered the DMA enabling.

Please CC all correspondence to my email, since I don't subscribe to
Linux-Kernel.  Thanks!

xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Josh Straub τΏτ [e-mail]