Re: [PARPORT] ppdev and ECP

From: Tim Waugh (
Date: Tue Oct 09 2001 - 07:08:49 EDT

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    On Tue, Jul 24, 2001 at 09:41:53PM +0200, Julien wrote:

    > Now I'd like to use interrupts, but it doesnot work. I put
    > "irq=auto", but select() never comes back. I can read data using
    > read(), and I can read as many data as I want there is no problem.
    > I have a logic analyzer, and there should be an IRQ because
    > PeriphClk (nAck) goes low to initiate the transfer. How can I enable
    > them ? I saw functions in the parport-lowlevel.txt so can I do it
    > through ppdev or is that made automatically ?

    When you do a PPCLAIM ioctl, interrupts are turned on, so it ought to
    work. Do the numbers go up in /proc/interrupts?

    > When the interrupts will be enabled, will the FIFO be used ? Can I
    > set up the interrupt to occur only when the FIFO is full ?

    The FIFO will be used if you have compiled the kernel with
    CONFIG_PARPORT_PC_FIFO enabled, told parport_pc which interrupt to use
    with irq=X (or 'auto'), not passed dma=nofifo, AND parport_pc has
    detected hardware that it can use.

    At user level, you don't get to know about interrupts caused by FIFO


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