RE: [hpoj-devel] scan lockups with PSC500

[DG <dg...@um...>]

From: pa...@rc... (David Paschal)
> Hi, Daniel.  Thanks for getting me the debug output.  Unfortunately there
> was a gap right at the place where it became interesting (where it changes
> from event9/get_nibble/event11/event6 to mlcpp_intr).  If you happened to
> save other debug logs (or if you try this again), could you check to see
if
> any of the other logs show this transition better?  If you see a line such
> as "get_nibble(c60b_intr c60b1160", that is a sign of a gap.

Unfortunately, all of the log files I've made have this problem, and setting
LINEBUF didn't seem to help.

> It occurred to me that after we set event 7 or 12 (nAutoFd=0) in
get_nibble,
> perhaps the peripheral doesn't respond with event 9 (nAck=0) until after
we
> drop out of the poll loop contained within the PAR_WAIT_SET_CLEAR macro.
> I don't know how long it is until mlcpp_intr gets called again to retry
the
> poll loop, but perhaps the peripheral times out in the meantime and backs
> out of event 9, such that we time out for event 9.  To test this theory,
> please try increasing the value of SHORT_WAIT, which is currently 500
> iterations of the loop in PAR_WAIT_SET_CLEAR.  I'm not sure what would be
a
> better value, but you could experiment with several, such as 5000 or
10000.
> If it's too large you may start to notice that your machine gets sluggish
> due to spending a lot of time in kernel mode.

Very sluggish, but still hangs.  And the debug output still gets cut off
occasionally.  I'm not sure how to fix that.

> Another interesting test would be to log the return code of
parStatusRead()
> right before setting event 7/12, and again after
"SET_STATE(l,9,BUSY_TIME);"
> but before "PAR_WAIT_SET_CLEAR(l,0,PAR_STATUS_NACK);".  Any status line
> changes after event 7/12 might further suggest a peripheral-side timeout.

Event 7/12 is a parControlSetClear() which never calls parStatusRead().  Do
you mean parControlRead() or do you mean check it during event 6 (which
comes just before event 7, I presume)?  It looks like parStatusRead() gets
called in PAR_WAIT_SET_CLEAR.

Does the 1284.4 specification outline all these events?  It would be very
helpful to have a flowchart or state diagram showing how all these events
are supposed to occur.

--
Daniel
ZZZ-dgun-ZZZ-@-ZZZ-umpire.com-ZZZ
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