[PARPORT] slight pt.c modification + request for epat/interrupt info

Bradley Rosser (b_rosser@yahoo.com)
Thu, 19 Aug 1999 03:15:18 -0700 (PDT)

Hi. I've found that I've been able to improve the performance/
streaming somewhat for my external HP Colorado 14GBe tape drive by
making a change to pt_poll_dsc() in pt.c, moving the
from the beginning of its polling loop to the end of the loop body.
Streaming periods are longer (at the lower speed of the drive) and
throughput has improved.

I'm running Linux 2.0.36; I did a diff of 2.2.6 source and I don't
think pt_poll_dsc() was any different in that kernel. My apologies
if this change is old news (or if the position of the pt_sleep is
vital for some reason!).

Could anyone help me with the following?

1. Is there any instruction/command which one could use to tell
    the HP Colorado drive (Shuttle EPAT driver) not to bother trying
    each track initially at its highest speed setting? It drives me
    crazy how it goes through about 7 cycles of 2-3 seconds on high
    speed at the beginning of each track before it settles down
    and streams at a lower tape speed.

2. I'd like to have a shot at getting pt.c to work with interrupts,
    rather than use polling, but I don't have a clue on how to get
    started. From what I've read of the parport web site the
    parport module allows interrupts, but I haven't found any
    of any drivers (in my 2.0.36 kernel) which use parport. The
    lp driver uses interrupts (for writing to the printer) but with
    no comments I'm completely lost in trying to work out how it
    does it (and I don't think it uses parport).

    If someone could tell me where I could get started - 'so-and-so
    driver uses interrupts' or 'this uses parport and interrupts' -
    I would be very grateful. Is parport used much in 2.0.36, or
    should I move to 2.2.x to see it in all its glory?

    Could anyone point me out to documentation (parallel port specs?)
    which might help me decode all the magic ports and numbers used
    in the drivers?

Sorry to be such a novice,

Brad Rosser

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This archive was generated by hypermail 2.0b3 on Thu 19 Aug 1999 - 06:20:23 EDT