Re: 2.1.111: IDE DMA disabled...BLAH...BLAH...

Mark Lord (
Wed, 29 Jul 1998 19:44:26 -0400

Andre M. Hedrick wrote:
> > The IDE driver already does the Most Sensible things by default,
> > leaving the chipset and drive settings as set-up by the BIOS.
> However, consider the case of a BIOS-less chipset on an offboard
> card that must be programmed. The chipset is native to UDMA
> and is backwards compatable. In all cases the pci-config data
> must me set for any mode regardless of the drive's capablities.
> Without take this step, an UDMA would register in PIO 0 strength.
> > If DMA fails, the IDE driver automatically falls back to PIO mode,
> > without loss of data or corruption of any sort.
> This is a good thing, and it works with the case stated above.
> Since I am having trouble getting the method in question functional,
> it is nice that the breakout of a failed (U)DMA results in a clean
> transition back to PIO status.

You can do this yourself from user-level, safely, after booting,
by using the /proc/ide/*/config interface. See ide-proc.c for info.

The (ex-)Linux IDE guy

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