Cannot enable DMA on SATA drive (SCSI-libsata, VIA SATA)

Using 2.6.8.1. DMA works fine on /dev/hda (PATA, CD burner).

When I try to enable it for my SATA drive (which is performing horribly bad -- 80-90% CPU load on an AMD64 3200+ during copy of large files) I get this error:

# hdparm -d 1 /dev/sda

/dev/sda:
setting using_dma to 1 (on)
HDIO_SET_DMA failed: Invalid argument

Tried different commands:

# hdparm -X66 -d1 /dev/sda

/dev/sda:
setting using_dma to 1 (on)
HDIO_SET_DMA failed: Invalid argument setting xfermode to 66 (UltraDMA mode2) HDIO_DRIVE_CMD(setxfermode) failed: Invalid argument

hdparm -d /dev/sda gives absolutely no information.

The chipset is VIA82Cxx (ASUS K8VSE Deluxe motherboard). Disk is Maxtor 6Y200M0.

Seen in /proc/scsi/scsi like this:

Host: scsi0 Channel: 00 Id: 00 Lun: 00
Vendor: ATA Model: Maxtor 6Y200M0 Rev: YAR5
Type: Direct-Access ANSI SCSI revision: 05

I also have the Promise controller, which I can use use a regular SATA controller (not RAID as is default). Should I attach it to it instead (I'd rather not if it can be avoided).

dmesg info:

libata version 1.02 loaded.
sata_via version 0.20
ACPI: PCI interrupt 0000:00:0f.0[B] -> GSI 20 (level, low) -> IRQ 20 sata_via(0000:00:0f.0): routed to hard irq line 10
ata1: SATA max UDMA/133 cmd 0xE400 ctl 0xE002 bmdma 0xD000 irq 20
ata2: SATA max UDMA/133 cmd 0xD800 ctl 0xD402 bmdma 0xD008 irq 20
ata1: dev 0 cfg 49:2f00 82:7c6b 83:7f09 84:4003 85:7c69 86:3e01 87:4003 88:407f
ata1: dev 0 ATA, max UDMA/133, 398297088 sectors: lba48
ata1: dev 0 configured for UDMA/133
scsi0 : sata_via
ata2: no device found (phy stat 00000000)
scsi1 : sata_via
Vendor: ATA Model: Maxtor 6Y200M0 Rev: YAR5
Type: Direct-Access ANSI SCSI revision: 05
SCSI device sda: 398297088 512-byte hdwr sectors (203928 MB)
SCSI device sda: drive cache: write back
/dev/scsi/host0/bus0/target0/lun0: p1 p2 < p5 p6 p7 p8 p9 p10 p11 p12
p13 >
Attached scsi disk sda at scsi0, channel 0, id 0, lun 0
Attached scsi generic sg0 at scsi0, channel 0, id 0, lun 0, type 0

DMA is always enabled.

Jeff

Hello,

just a 'me too' e-mail... I have Master2-FAR mobo, VIA/KT800 chipset.
IDE disk runs like a charm but SATA disks consume big amount of cpu
time (which is spent in iowait). The system behaves exactly as with
old IDE disk and DMA disabled... everything is slow when data is transferred to/from disk.

I have played with various settings, io schedulers, acpi... but haven't found anything useful so far..

Regards,
Petr

Make sure you enable the SCSI later, SATA drivers and VIA SATA driver otherwise you may end up using PIO with the PCI generic IDE driver.