Re: [PARPORT] PCI ECP Parallel port card questions

From: Tim Waugh (
Date: Sun Jun 03 2001 - 06:57:46 EDT

  • Next message: "Re: [PARPORT] PCI ECP Parallel port card questions"

    On Sun, Jun 03, 2001 at 11:45:47AM +0100, Jesús Torres wrote:

    > On Sat, Jun 02, 2001 at 06:31:20PM +0100, Tim Waugh wrote:
    > > But why switch away from a DMA ECP-capable onboard port anyway?
    > I have a throughtput of 500 KB/s with a onboard port.

    Using DMA?

    > I think that using a PCI card I will solve my speed problems with a
    > better access time.
    > Is it true?

    For things like inb/outb, yes, as I understand it.

    > If I understand you the Linux driver need a small tweak and some
    > testing to get it using PCI interrupts. I will can to use PIO access
    > mode with it.

    Yes. In parport_pc.c there is a comment like 'TODO: Test if sharing
    interrupts works', and below that a PARPORT_IRQ_NONE. That needs to
    be changed to 'irq', or 'autoirq', or something, and the actually IRQ
    registration needs to use the SHARED flag. Then it has to be tested
    to see if it actually works, or if it upsets something in parport_pc
    or any of the high-level drivers.

    > Is The DMA support a restriction of the Linux driver or of the PCI bus?

    The Linux driver. Basically, as soon as someone gets PCI interrupts
    going in the driver, DMA support will follow naturally.


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