Re: [PARPORT] ECP mode transfers in 2.4.x kernels

From: Dave Strauss (
Date: Mon Aug 27 2001 - 12:15:31 EDT

  • Next message: Philip Blundell: "Re: [PARPORT] ECP mode transfers in 2.4.x kernels"

    On Mon, 27 Aug 2001 17:04:04 +0100, Philip Blundell <> wrote:
    > >[...]
    > >+#else /* CONFIG_PARPORT_PC_FIFO */
    > >+ printk (KERN_INFO "lp%d: compatibility mode\n", minor);
    > >+ lp_table[minor].best_mode = IEEE1284_MODE_COMPAT;
    > >+#endif /* CONFIG_PARPORT_PC_FIFO */
    > Why do you need to explicitly check CONFIG_PARPORT_PC_FIFO? That doesn't seem
    > like the kind of thing that drivers should be doing. I think the parport
    > ieee1284 code and/or parport_pc itself should arrange for things to behave
    > "properly" regardless of that option. If parport_pc can't do ECP in any
    > meaningful way without the FIFO being enabled, maybe it should fiddle the
    > advertised modes to not claim ECP support at all.
    > p.

    In the long run I think you're right, but I was trying to deal with
    the fact that the parport ECP mode doesn't work unless DMA is used. I
    don't have any problem removing the test as long as it's coupled with
    appropriate changes to parport. Perhaps parport should just fail the
    negotiate-to-ECP request unless FIFO/DMA support is turned on (and the
    hardware supports it!). I'd be happy to submit a set of coupled
    patches if that's the right thing to do.

    BTW, Windows machines won't even attempt to do ECP mode transfers unless
    the hardware supports DMA, no matter what your BIOS settings may be.
    Perhaps we should learn from them :-)

    -- Dave Strauss

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