umax_pp_low: ppdev

From: Tim Waugh (
Date: Wed Jun 06 2001 - 01:41:46 PDT

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    In umax_pp_low, the following code is wrong:

              /* me check if parport is does ECP */
              mode = IEEE1284_MODE_ECP;
              if (ioctl (fd, PPSETMODE, &mode))
                  DBG (16, "umax_pp: port '%s' hasn't ECP\n", parport_name);

    That isn't checking what the port can do at all, but what the driver
    will let you do. The successful PPSETMODE just means that the next
    write() you do will cause the driver to write the data out using ECP.

    The only circumstance under which it might fail really is that

    (a) the port doesn't have hardware ECP support, _AND_
    (b) the kernel's IEEE 1284 implementation wasn't configured when you
        built it


              /* we try to set EPP 1.7 first */
              mode = IEEE1284_MODE_EPPSL;
              if (ioctl (fd, PPSETMODE, &mode))

    The comment is wrong.

    If you want to find out what the _hardware_ can do, you want to use
    the PPGETMODES ioctl (and treat errors as 'not telling you').


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