Re: [PARPORT] DMA in ECP and EPP mode

From: Tim Waugh (
Date: Thu Apr 19 2001 - 03:06:18 EDT

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    On Wed, Apr 18, 2001 at 11:06:15PM +0200, Tommy Kjellqvist wrote:

    > Does the parport driver use DMA in both EPP and ECP mode?

    No. I don't think that there are any chips which support DMA in EPP.

    The parport driver will use DMA for ECP if

    (a) it's configured to in the kernel (CONFIG_PARPORT_PC_FIFO),
    (b) the hardware is there for it to use, and
    (c) the module parameter 'irq=auto' (or kernel command line parameter
        parport=auto) is used.

    > Whitch mode can be expected to deliver the highest performance?

    It depends on your application, I think. ECP seems to be quite
    popular for newer devices though.

    > Is there any important differences between the two modes except the
    > fact that when transfering data from a peripherial to the host using
    > ECP the peripherial initiate the transfer?

    Well, they are just different protocols. With both modes the
    peripheral gets to say whether it has data to transfer, AFAIR.


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