Re: [PARPORT] PCI ECP Parallel port card questions

From: Tim Waugh (
Date: Sat Jun 02 2001 - 13:31:20 EDT

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

    On Sat, Jun 02, 2001 at 06:03:33PM +0100, Jesús Torres wrote:

    > In <Low ECP speed> message I saw that all outb take 2uS (500 KB/s)
    > and all outsb take 128uS to read 16 bytes using a onboard port.
    > I haven't solved the problem but because 500 KB/s is too slow I will
    > go to use a PCI parallel port card. I need a throughtput of 1 MB/s.
    > I have any questions:
    > - I read that there isn't DMA support on PCI. It has bus master support

    That's true for the Linux driver, as a side effect of not using PCI
    interrupts yet. It just needs a small tweak and some testing to get
    it going though, so long as the PCI card has ECP support (and it's
    also supported by the Linux driver).

    But why switch away from a DMA ECP-capable onboard port anyway?

    > Do I must use PIO access code?

    (The Linux driver also doesn't use PIO unless it has an interrupt it
    can use; fixing this is just a question of coding it up though.)

    > - In many EPP parports there are 32 bit transfers support.
    > Can I use 32 bit transfers in ECP parports?

    No. But if you are planning on using DMA it doesn't matter anyway,
    since 32-bit accesses just cut down on the 'outb' overhead.


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