RE: [hpoj-devel] SMP patches?

[PASCHAL,DAVID (HP-Roseville,ex1) <dav...@hp...>]

Robert G. Brown wrote:
> So I was (and still am) getting the following message from the
> mlcpp_transmit() routine even with the patched driver:
> 
> Dec  1 18:23:30 lucifer kernel: mlcpp0: mlcpp_transmit while TX busy
> 
> I still suspect an SMP problem but I'm not certain.  It could 
> either be
> that having two processors allows a second transmit interrupt to occur
> before the line is fully clean from the first -- not necessarily a
> proper spinlock failure but a mix of spinlock failure and handshaking
> failure.  Or something.  It could also just be some sort of 
> flow control
> failure all by itself -- with megabyte sized images, the 
> printer may be
> trying to say "enough" while it processes what it's got but the flow
> stop may not be getting through.

Hi, Robert.  It also sounds like an SMP problem to me.  Another thing you
could try is to boot the SMP box with the "nosmp" kernel parameter, which
puts it into UP mode.  I'll attempt to look into the problem in the near
future, but I'll have to dig through a part of the code I'm not currently
very familiar with.

> Any helpful suggestions beyond that would be appreciated, especially
> from folks who already know why the transmit while TX busy 
> message might
> be occurring.  I did already note the new requirement that the printer
> port be configured EPC (mine was SPP in the bios) and reset it but it
> made no difference.  I'm guessing that was more for scanner function
> anyway.  This seems like an overrun failure of the plain old printer
> device.
Are you able to scan successfully, particularly at higher resolutions which
cause more data to be transferred for a longer period of time?  Of course,
that's in the opposite direction, but even then there are small amounts of
PC-to-printer data being transferred.

David