Re: [PARPORT] new ppdev operations

From: Tim Waugh (
Date: Tue Jun 19 2001 - 12:10:00 EDT

  • Next message: Uwe Bonnes: "Re: [PARPORT] new ppdev operations"

    On Tue, Jun 19, 2001 at 05:46:43PM +0200, Ronnie Arosa wrote:

    > I'm working with an Oxsemi's chipset. I've got a development board and I
    > would like to test the chip it incorporates.

    Well, ppdev isn't really for this sort of thing: it's for writing
    device drivers for peripherals really.

    I would suggest that for this debugging need you should just do an
    inb() on the right I/O address in user space (write a small ioperm
    program, or use /dev/port).

    > The development board was
    > not correctly integrated and designers have forgot some pull-up
    > resistences need to work in some modes (mode compatible for example). So
    > instead of just siiting down waiting for receiving the new board, I
    > would like to start testing with the modes that the chip is supposed to
    > work. I've changed parport_pc.c to input the ECP mode to the ECR
    > register at initialization time. But after initialization ECR returns to
    > PS2 mode, incomprensiblemente.

    I think that the ECR gets reset to a 'normal' value more often than
    necessary in parport_pc. I have an item on my todo list reminding me
    to look at it, but I haven't yet. This sounds like it might be
    causing your problem.

    I'm pretty sure that there is a debugging function now in parport_pc
    for dumping the state of the registers: dump_parport_state (in
    parport_pc.h). Can you use that to help track down what's going on?


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