[PARPORT] LaserJet 4M: IEEE nibble mode failure

From: Ferenc Wagner (wferi@bolyai1.elte.hu)
Date: Sun Sep 03 2000 - 07:48:59 EDT

  • Next message: Tim Waugh: "Re: [PARPORT] LaserJet 4M: IEEE nibble mode failure"


    I'm fighting to establish bidirectional communication between a HP
    LaserJet 4M printer and a Linux machine. I tested the whole thing under
    Windows 95 with the enclosed HP Explorer software, namely with RCP4: the
    Remote Control Panel runs all right and performs as expected.

    Under Linux, it's not so good... The IEEE 1284 negotiation protocol is
    included in the Linux parport driver (I'v checked it against
    http://www.fapo.com/negoti8.htm; hope that's reliable). After some
    debugging I found that the problem arises at Step 6 (according to the
    above webpage): when Ack goes high, the status register reads 0xef, that
    is: Busy low, nAck high, PE high, Select low, nError high. According to
    the standard, PE should be low, but that I don't care. But Select being
    low means ``mode not available'', which is impossible for nibble mode,
    isn't it? I forgot to say that I sent 4 as Extensibility Data Byte; but it
    hardly matters: the result is the same for everything, I tried.

    The BIOS setting for the parallel port is SPP. What can be the problem?
    I've even tried several different timing schemes for the length of the
    Strobe pulse; it didn't help... Perhaps this printer just won't send me a
    Device ID... but is there a way then get some info back? My aim is to
    read back the page counter, anyway.

                                            Thanks: Feri.

    PS: I modified the 2.2.12-20 kernel's parport module to get some more
    debugging output. All the changes were made in
    drivers/misc/parport_ieee1284.c, function parport_ieee1284_nibble_mode_ok.
    Here it is:

    /* Test if the peripheral is IEEE 1284 compliant.
     * return values are:
     * 0 - handshake failed; peripheral is not compliant (or none present)
     * 1 - handshake OK; IEEE1284 peripheral present but no data available
     * 2 - handshake OK; IEEE1284 peripheral and data available
    int parport_ieee1284_nibble_mode_ok(struct parport *port, unsigned char
            printk (KERN_INFO "%s: checking for nibble_mode 0x%02x\n",
            /* make sure it's a valid state, set nStrobe & nAutoFeed high */
            parport_frob_control (port, (1|2), 0);
            parport_write_data(port, mode);
            /* nSelectIn high, nAutoFd low */
            parport_frob_control(port, (2|8), 2);
            if (parport_wait_peripheral(port, 0x78, 0x38)) {
                    printk (KERN_INFO "%s: handshake failed, status=0x%02x\n",
    port->name, parport_read_status (port));
                    parport_frob_control(port, (2|8), 8);
                    return 0;
            printk (KERN_INFO "%s: handshake OK\n", port->name);
            /* nStrobe low */
            parport_frob_control (port, 1, 1);
            udelay(1); /* Strobe wait */
            /* nStrobe high, nAutoFeed low, last step before transferring
             * reverse data */
            parport_frob_control (port, (1|2), 0);
            /* Data available? */
            if (parport_wait_peripheral (port, PARPORT_STATUS_ACK,
                    printk (KERN_INFO "%s: timed out waiting for ACK go
    high\n", port->name);
                    printk (KERN_INFO "%s: response OK\n", port->name);
            printk (KERN_INFO "%s: status=0x%02x\n", port->name,
    parport_read_status (port));
            return (parport_read_status(port) & PARPORT_STATUS_ERROR)?1:2;

    And after this the kernel log reads:

    Sep 2 19:21:07 bolyai1 kernel: parport0: PC-style at 0x378 [SPP,PS2]
    Sep 2 19:21:07 bolyai1 kernel: parport0: checking for nibble_mode 0x04
    Sep 2 19:21:07 bolyai1 kernel: parport0: handshake OK
    Sep 2 19:21:07 bolyai1 kernel: parport0: response OK
    Sep 2 19:21:07 bolyai1 kernel: parport0: status=0xef
    Sep 2 19:21:07 bolyai1 kernel: parport0: no IEEE-1284 device present.

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