Re: UDMA is NFG on Ultra33 (CMD646 in disguise)

David S. Miller (davem@dm.cobaltmicro.com)
Tue, 24 Nov 1998 05:38:32 -0800


Date: Tue, 24 Nov 1998 02:14:08 +0000
From: Mark Lord <mlord@pobox.com>

I dunno what to make of it, other than
"UDMA is broken on the Promise Ultra33" card.

If you look at the cmd646.c driver we use on Sparc (and which btw
should only be available to use on Sparc, someone please prevent
non-sparc users from using this driver ASAP!) you'll see that UDMA is
know to be unusable on 646U chipsets, 646U2 chipsets are fine.

The 646U issue is a timing problem during the UDMA handshakes, you can
solder up a workaround onto the asic (yes, I've done it) but then it
will only work with Seagate drives.

Later,
David S. Miller
davem@dm.cobaltmicro.com

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