Enabling DMA for IDE broke for my laptop.  If I turn on DMA, my laptop
stalls doing partition checks.  Keyboard is responsive, mouse is fine,
etc, all normal except it looks like the partition check just went to
sleep with the HD LED on.  It's the same place it hangs if I enable the
PIIX tuning however if I enable PIIX tuning, the machine locks up hard
and must be powered off to reboot.

Attached is lspci -vv output.

block: 352 slots per queue, batch=88
Uniform Multi-Platform E-IDE driver Revision: 6.31
ide: Assuming 33MHz system bus speed for PIO modes; override with idebus=xx
PIIX4: IDE controller on PCI bus 00 dev 39
PIIX4: chipset revision 1
PIIX4: not 100% native mode: will probe irqs later
     ide0: BM-DMA at 0xffa0-0xffa7, BIOS settings: hda:DMA, hdb:pio
     ide1: BM-DMA at 0xffa8-0xffaf, BIOS settings: hdc:DMA, hdd:pio
hda: FUJITSU MHG2102AT, ATA DISK drive
hdc: MATSHITA CR-175, ATAPI CD/DVD-ROM drive
ide0 at 0x1f0-0x1f7,0x3f6 on irq 14
ide1 at 0x170-0x177,0x376 on irq 15
hda: host protected area => 1
hda: 19640880 sectors (10056 MB) w/512KiB Cache, CHS=1222/255/63
hdc: ATAPI 24X CD-ROM drive, 128kB Cache
Uniform CD-ROM driver Revision: 3.12
Partition check:
  /dev/ide/host0/bus0/target0/lun0: p1 p2 p3

It will hang before printing "p1"

David

Alan Cox wrote:

 >Linux 2.4.19pre8-ac3
 >o	Kbuild fixes					(Keith Owens)
 >o	Fix eepro100 bug/typo				(Michael Rozhavsky)
 >o	Intel 845G GART support				(Graeme Fisher)
 >o	Fix tasklet disable/kill in pppoatm		(Luca Barbier)
 >o	Add another PCI ident to the acenic driver	(Eric Smith)
 >o	Major IDE updates				(Andre Hedrick)
 >
 >