From: Peter Pregler (
Date: Fri May 12 2000 - 06:07:34 EDT

  • Next message: Sebastian Leske: "[PARPORT] linux-kernel / plip.c : Small correction (?)"

    On Thu, May 11, 2000 at 09:37:03PM +0100, Tim Waugh wrote:
    > On Thu, May 11, 2000 at 02:15:52PM -0400, Derek Bouius wrote:
    > > I really need read DMA for my device.
    > See the archives of this list for why PIO reading hasn't been done yet
    > (I have the fix but it isn't properly integrated yet). As for DMA, I
    > think it just hasn't been tested much.

    I did some pio-reading tests and I could read a single frame but the
    port was not switched back correctly, at least not for my device (a
    CPiA based webcam). In any case, the block-read interface is not
    suitable for my purpose. A webcam delivers a stream of indefinite
    length (due to compression). The end-of-stream is a data pattern in the
    stream. The current read-functions do ieee-mode switching after reading
    blocks which must not happen for the webcam. So I see no way to
    implement streaming read with the current interface. I will try to show
    some working code that implements what I need.

    AFAIK, there is no dma-read code in the current 2.3.x-kernels.


    Even the thought that a ship was waiting to take him back to Earth
    did not wipe out the sense of loss he felt at that moment.

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