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

From: Philip Blundell (
Date: Mon Aug 27 2001 - 13:28:19 EDT

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

    >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.

    Can you be more specific about what goes wrong with it? In theory it should
    be possible to negotiate into (and use!) ECP mode on any port -- if hardware
    assistance isn't available, parport will perform ECP protocol in software.
    >From the lp point of view using software-ECP is probably a bad thing for
    performance, but it should still work the same and I think we should retain
    the ability for drivers to do this if they want to, say if some particular
    peripheral functionality is only available in ECP mode.

    Having thought about it some more, I'm now convinced that parport_pc should
    only set bits in port->modes when a particular mode is both supported by the
    underlying hardware and available in this configuration. It sounds like there
    might still be other bugs, but that should be enough to make your particular
    problem go away. Could you produce a patch to do that, plus a modified
    version of your lp.c change?


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