From owner-freebsd-current  Tue Dec 21 13:59:45 1999
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From: Soren Schmidt <sos@freebsd.dk>
Message-Id: <199912212159.WAA07522@freebsd.dk>
Subject: Re: Problems with the ATA-driver
In-Reply-To: <19991221215114.977C71CCE@overcee.netplex.com.au> from Peter Wemm at "Dec 22, 1999 05:51:14 am"
To: peter@netplex.com.au (Peter Wemm)
Date: Tue, 21 Dec 1999 22:59:20 +0100 (CET)
Cc: havoc@Cal30B054.student.utwente.nl (Theo van Klaveren),
	freebsd-current@FreeBSD.ORG
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It seems Peter Wemm wrote:
> 
> Same here, but with a toshiba laptop disk.  I have to comment out a version
> test in ata-disk.c to get it to work.

I've just a few hours ago committed a change that does this...
> 
> --- ata-disk.c  1999/12/18 20:06:30     1.46
> +++ ata-disk.c  1999/12/21 21:48:28
> @@ -117,7 +117,7 @@
>  static __inline int
>  udmamode(struct ata_params *ap)
>  {
> -    if ((ap->atavalid & 4) && ad_version(ap->versmajor) >= 3) {
> +    if ((ap->atavalid & 4) /* && ad_version(ap->versmajor) >= 3 */) {
>         if (ap->udmamodes & 0x10) return (ap->cblid ? 4 : 2);
>         if (ap->udmamodes & 0x08) return (ap->cblid ? 3 : 2);
>         if (ap->udmamodes & 0x04) return 2;

> Without this, ata thinks is's an ATA-0 disk and tries to use DMA mode.
> However, it hangs with:
> 
> mounting root /dev/ad0s1a
> ata-master: lost disk contact
> ata: resetting devices ..
> 
> and never gets to "done" just like you.  If I remove the ATA version test and
> just have it look at the "I support UDMA" bit, it runs in UDMA33 mode and
> works fine.  I suspect that if it got a CRC error and tried to do a fallback
> that it would hang there too, but I have not seen any.
> 
> I think the (plain) DMA code is broken somewhere.

Its the same code as is used i UDMA mode :), its only the timing thats
different and the setup of the controller. It will never fall back
to a lower DMA rate, as lots of chipsets can't do that, it will always
fall back to PIO, which should work...

-Søren


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