hdparm disk problem?

[Jack Liu]

hi,all
  I encountered a problem with VIA VT6410 device, it is a IDE RAID chip. I am using it on a MPC8241 platform. Initially, it is 
	VP_IDE: VIA vt6410 (rev 06) IDE UDMA133 controller on pci00:0d.0
	VP_IDE: 100% native mode on irq 1
	set dma via_enabled:0x3
    	ide0: BM-DMA at 0xfed0-0xfed7, BIOS settings: hda:pio, hdb:pio
	set dma via_enabled:0x3
    	ide1: BM-DMA at 0xfed8-0xfedf, BIOS settings: hdc:pio, hdd:pio
	Probing IDE interface ide0...
	hda: HTS548040M9AT00, USI: hda: HTS548040M9AT00, ATA DISK drive
	Set Drive parameter.
	ide_timing_compute returns OK.
	Set speed.

	And system starts with PIO mode, not DMA. So I used hdparm -d1 /dev/hda command to force it into DMA mode. Yet sometimes disk data corrupts. I am wondering the reason? And can someone told me the process that how DMA is enabled in a disk when booting up? Is it the responsibility of the driver or the script?
	The kernel version is 2.4.21, disk is Seagate disk and moxtor disk.

　　　　　　　
Best regard
Jack liu