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

From: Dave Strauss (
Date: Thu Aug 23 2001 - 11:31:50 EDT

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

    On Thu, 23 Aug 2001 16:08:55 +0100, Tim Waugh <> wrote:
    > On Thu, Aug 23, 2001 at 10:07:28AM -0400, Dave Strauss wrote:
    > > This may or may not help, depending on how big the chunks are that get
    > > passed into lp. If the application is sending things in small pieces,
    > > increasing LP_BUFFER_SIZE isn't going to help much.
    > Right, and a quick test shows that LPRng (for example) likes to write
    > one page at a time. :-(
    > > Do you mean the "preempt" in the parport device structure? So, lp
    > > would claim parport on lp_open(), put it into ecp mode, and leave it
    > > both claimed and in ecp mode until lp_release(). Is that what you
    > > mean? One problem -- can't the preempt function get called at any
    > > time? What if it gets called in the middle of a data transfer (or in
    > > the middle of any other lp entrypoint, for that matter)?
    > The preempt function doesn't have to give up the port right away. It
    > can make a note that it should release it 'soon'. Then at the end of
    > the entry points, you can check the flag and release the port if
    > necessary.
    > Tim.
    > */
    OK, that could work. Is there any way to lock access to the flag
    while I'm testing it and resetting it? What I'm envisioning is
    something like:

        if (!check_if_we_own_parport()) {
            parport_claim_or_block ();


        if (check_release_me_flag()) {

    I don't believe we need to lock access for the "ownership flag"
    because only one process can have lpx open at a time.

    -- Dave Strauss

    -- To unsubscribe, send mail to: --
    -- with the single word "unsubscribe" in the body of the message. --

    This archive was generated by hypermail 2b29 : Thu Aug 23 2001 - 11:42:20 EDT