Re: Issues with older wd* / IDE on various platforms

[Martin Husemann <martin%duskware.de@localhost>]

On Fri, Nov 13, 2020 at 11:06:56PM +0100, Jaromír Dole?ek wrote:
> There is no more automatic mode downgrade from DMA to PIO any more, so
> if the controller misadvertises DMA support, but it actually doesn't
> work, then I/O will just fail.

This should be easy to test by adding flags to the wd attachment in your
kernel config (no code changes needed).

For example I have some SD<->ATA converters and disable UDMA for them
like:

no wd* at atabus?
wd0 at atabus4 drive 0 flags 0x0f00     # disable UDMA on our SD card thingy
wd* at atabus? drive ? flags 0

To disable DMA and UDMA it would be flags 0x0ff0.

Martin