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From: Søren Schmidt <sos@sos.freebsd.dk>
Message-Id: <199708051827.UAA00589@sos.freebsd.dk>
Subject: Re: ide_pci, Tyan S1563S, and busmastering dma
In-Reply-To: <Pine.NEB.3.96.970805085022.436A-100000@samthedog.gold.tc.umn.edu> from dave adkins at "Aug 5, 97 09:47:27 am"
To: adkin003@gold.tc.umn.edu
Date: Tue, 5 Aug 1997 20:27:31 +0200 (MEST)
Cc: current@FreeBSD.ORG
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In reply to dave adkins who wrote:
> 
> Two things prevented the my Tyan S1562D from starting up in busmastering
> mode with FastDMA. 
> 
> 1) The conditional in generic_dmainit (ide_pci.c) was two restrictive to
> allow the Seagate CFA2161A to be recognized as DMA capable.
> 
> 2) The Award bios (v4.01) does not enable FastDMA.
> 
> When generic_dmainit is changed to allow PIO mode 3 drives and piix3
> configuration is added to ide_pci_attach to enable enable FastDMA, the
> drive functions fine, and interrupt overhead as seen in sysctl -vm is
> about as low as for my NCR pci scsi. 
> 
> I also verified that the drive was, infact, using DMA by inserting counter
> in wdstart where wdd_dmastart kicks off the DMA. The counter shows usage
> for each of the configured drives. I assume that if I get no messages from
> the driver, the setup modes for the piix3 and the drives remain
> unchanged.
> 
> What are the chances that the code could be changed to have configuration
> options to 1) relax the drive mode restrictions, and 2) force FastDMA? For
> now I just apply my own patch when I update my sources. 

Lets have your patches, and we can pretty fast determine if it is safe
to use...

> The wd driver with FastDMA enabled has been working well for the past
> couple of days (since the SMP fix). 

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Søren Schmidt               (sos@FreeBSD.org)               FreeBSD Core Team
                Even more code to hack -- will it ever end
..