Subject: Re: CF/IDE performance problem...
To: M. Warner Losh <>
From: Matthew Orgass <>
List: tech-kern
Date: 11/26/2005 22:16:10
On 2005-11-26 wrote:

> I have seen 64MB cards that support WDMA.  I've not seen any of the
> bigger ones that claim to support UDMA mode when used in true IDE
> mode.  Which brands are you seeing that support this?  I thought I saw
> somewhere in the spec that the maximum was just WDMA, but it has been
> a while since I looked.

  Ultra DMA was added in the latest version of the CF spec (revision 3).
The TwinMOS Ultra-X "70X" data sheet claims to support UDMA 4 (the "140X"
version datasheet claims UDMA 2).  I got one of these in 1GB and it
doesn't report any DMA capability with the adaptor I have, presumably
following the spec.  I also saw a more expensive industrial CF card that
made the same claim, however it looks like I forgot to bookmark it.
PQI and Apacer have cards that claim UDMA mode 2 support.

> You can turn the ones that don't support DMA into ones that do with a
> slight rewiring of the controller.  The cards that my company produced
> for our internal use just needed to have the following modifications
> made to them to make DMA start working.  I had to connect pin 43 of
> the CF connector to pin 21 of the IDE connector.  Ditto with 44 and
> 29.  IIRC, I also needed to cut the grounding on the IDE end of either
> 21 or 29.  Your milage may vary, so be careful before doing this.

  I could probably manage the IDE side, but I know my soldering skill is
not up to those tiny CF pins :).  It doesn't look like either pin is
grounded on my adaptor.  It is also somewhat odd in that it has a pin 20
that apparently some systems can use for power.

  I ordered a couple of DMA connected adaptors from Sealevel.  I'll post
to netbsd-users how it goes.  I'll also look into adding some translate
sector reporting to atactl.

Matthew Orgass