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From: Soren Schmidt <sos@spider.deepcore.dk>
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In-Reply-To: <200308271914.59403.mistry.7@osu.edu>
To: Anish Mistry <mistry.7@osu.edu>
Date: Thu, 28 Aug 2003 08:24:07 +0200 (CEST)
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cc: freebsd-current@FreeBSD.ORG
Subject: Re: ATAng no PIO fallback?
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It seems Anish Mistry wrote:
-- Start of PGP signed section.
> On Tuesday 26 August 2003 10:27 pm, Anish Mistry wrote:
> > After removing atapicam from my kernel, so no panics on boot I decided to 
> see
> > it DMA was fixed for my CD/DVD combo drive.  I changed the
> > hw.ata.atapi_dma="0"
> > to hw.ata.atapi_dma="1" in my /boot/loader.conf.  After a reboot I tried to
> > access my cdrom drive, and got the following error messages, which is very
> > similar to the messages when trying to dma before ATAng:
> > Aug 26 22:09:34 littleguy kernel: acd0: WARNING - READ_CD recovered from
> > missing interrupt
> > Aug 26 22:09:34 littleguy kernel: acd0: WARNING - READ_CD UDMA ICRC error
> > (retrying request)
> > 
> > The problem is that before with DMA enabled it would try dma a few times 
> fail,
> > and then fall back to PIO, whcih though annoying still left the drive in a
> > useable condition.  Where as now the drive just stays stuck and unusable.
> > 
> > .....
> Anyone thinking about looking into this?  I'll just submit a PR, in a day or 2 
> if there is no resposne.
> Thanks,

There is no PIO fallback in ATAng (so far), if you know that your ATAPI device 
doesn't do DMA why on earth do you enable it ?

-Søren