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Date:      Mon, 21 Aug 1995 09:18:20 -0700 (PDT)
From:      Julian Elischer <julian@ref.tfs.com>
To:        luigi@labinfo.iet.unipi.it (Luigi Rizzo)
Cc:        freebsd-hackers@freebsd.org
Subject:   Re: How to abort a DMA transfer ?
Message-ID:  <199508211618.JAA23776@ref.tfs.com>
In-Reply-To: <199508210841.KAA13733@labinfo.iet.unipi.it> from "Luigi Rizzo" at Aug 21, 95 10:41:27 am

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> 2) the device is closed while the DMA is active (which is essentially
>    all the times) *and* there will be no further data coming from the
>    scanner (this is likely: the user knows he wants to close the
>    device, thus he stops scanning and then gives the appropriate
>    commands);

don't allow the close to complete  until the DMA has completed..

> 3) a new open is requested, possibly with different parameters, which
>    causes the need for a larger buffer; now I need to abort the
    previous transfer, free the old memory, and malloc a newer block.
> 
> > now)?  I would personally do everything in avoiding even touching such
> > a hot iron like the DMAC.
> 
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