[PARPORT] Parallel port ioctl()

From: peter.holmes@fopet-esl.com
Date: Tue Feb 25 2003 - 04:58:31 EST

  • Next message: Tim Waugh: "Re: [PARPORT] Parallel port ioctl()"

    Greetings all. I am a relative new-comer to parallel port interfacing and,
    for that matter, a new-comer to LINUX also.

    Maybe this isn't the place to ask my question but I seem to have exhausted
    -all- other avenues. You'll tell me I'm sure(!).

    I have written a bespoke ioctl() to communicate with a laboratory testing
    device (length of wool fibres). It only partly works because, I think, the
    kernel parallel port driver/module is clobbering it:
    If I toggle the input _ACK line low, without my code running on LINUX, the
    _STROBE output toggles with it. Not quite in sync, there's a ca. 5uS delay.

    One oddity is that my ioctl_foo_init() code allows me access to the Extended
    Control Register(s) and I can read the ECR as 0x35 - the default. But when I
    unload the ioctl_foo() I get a message in syslog telling me that the address
    space (at 0x778-77a) isn't valid.

    1) can I disable the parallel port driver without recompiling the kernel?
    - if not -
    2) do I need to recompile the kernel without parallel support?
    - if so -
    any suggestion as to the best place to look for (de)selecting kernel
    modules at compile time?
    There's plenty of information on compiling the kernel but little I could find
    on module selection.

    One more thought - I considered PLIP as a possible option but the suggestion
    is that it is now deprecated. Is this a common thought?

    Any help appreciated. I really don't want to be driven back to that other

    Peter Holmes

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