Re: [PARPORT] ppdev hangs on read

From: Tim Waugh (twaugh@redhat.com)
Date: Mon Nov 04 2002 - 05:54:51 EST

  • Next message: Charles Lepple: "Re: [PARPORT] reading/writing to the parallel port"

    On Mon, Nov 04, 2002 at 08:08:36AM +0100, stef wrote:

    > On Sat, Nov 02, 2002 at 06:08:32PM +0000, Tim Waugh wrote:
    > > On Mon, Oct 28, 2002 at 09:05:25AM +0100, stef wrote:
    > >
    > > > After putting some debug messages, I get:
    > > > Oct 28 08:44:51 xxxx kernel: parport_pc_epp_read_data(1) called
    > > > Oct 28 08:44:51 xxxx kernel: parport_pc_epp_read_data timeout
    > > > Oct 28 08:44:51 xxxx kernel: parport_pc_epp_read_data return 0 bytes
    > > > Oct 28 08:44:51 xxxx kernel: ppdev: pp_read (fct=2) data got 0 bytes
    > >
    > > Was that with O_NONBLOCK set or not? We need both, to compare.
    >
    > O_NONBLOCK was not set.
    >
    > >
    > > Tim.
    > > */
    >
    >
    > With O_NONBLOCK set, I get some timeouts:
    >
    > .....
    > Nov 4 07:28:45 xxxx kernel: parport_pc_epp_read_data return 1 bytes
    > Nov 4 07:28:45 xxxx kernel: parport_pc_epp_read_data(1) called
    > Nov 4 07:28:45 xxxx kernel: parport_pc_epp_read_data timeout
    > Nov 4 07:28:45 xxxx kernel: parport_pc_epp_read_data return 0 bytes
    !!!
    > Nov 4 07:28:45 xxxx kernel: parport_pc_epp_read_data(1) called
    > Nov 4 07:28:45 xxxx kernel: parport_pc_epp_read_data return 1 bytes
    > ......

    Why is there no 'pp_read data got 0 bytes' message at '!!!'? Also we
    need to know what happens after the first loop when O_NONBLOCK is not
    set. Are we looping in pp_read or somewhere else?

    Tim.
    */


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