[PARPORT] Re: amiga printing problems

From: Joerg Dorchain (joerg@dorchain.net)
Date: Thu Aug 30 2001 - 15:54:14 EDT

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    On Thu, Aug 30, 2001 at 08:10:07PM +1000, Ken Tyler wrote:
    > Putting udelay(3) in the parport_amiga.c write_data to hardware function
    > slows things down sufficently to produce correct printing, but putting any

    This points to handshake problems.

    > I can't see anything in parport_amiga.c in combination with ieee1284_ops.c
    > that supports a write -> strobe -> ack -> interrupt -> do it again loop.

    write something to the data register autmatically triggers the strobe
    (that is a hardware feature, you cannot influence the length of the
    strobe directly in software, i.e. it sets the strobe and unsets it after
    a certain fixed amount of time without any piece of software involved).
    When the device sets an ack, an interrupt is triggered (feature of the
    same hardware). As acknowledgement of this interrupt is handled by the
    generic interrupt routine, amiga_interrupt is merely a noop. (In contrast
    to e.g. mfc3_interrupt, where some bit has to be reset for the next
    interrupt to be allowed)



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