[PARPORT] ppdev user space driver

chris (clfletch@spawar.navy.mil)
Wed, 24 Nov 1999 08:21:04 -0800


     Thanks for your help with the ppdev user space driver.
I have built the 2.3.28 development kernel and have used it to
perform EPP data read transfers through the parallel port at data rates
around 340Kbytes/sec a lot better than the 140Kbytes/sec I was getting
I still believe the data read transfer rates are still slower than they
should be.
Additionally, I have also noticed some data dropouts that weren't there
with the
2.2 ppdev patches.

    After looking at the timing on a logic analyzer I noticed that
between reading in a bytes there is about a 3microsecond delay period
before the parallel port is ready to read in another byte. It maybe
coming from
clearing out timeout bit after each EPP read cycle. Is clearing the
timeout bit before
each data read cycle a necissity?

One final comment on the ppdev user driver. I noticed that there was
a pp_mmap function
in the pp_fops but it was NULL. Is there any plan on using the pp_mmap
file operation with
the ppdev user driver or is it a work in progress?

Thanks again for your help

-- To unsubscribe, send mail to: linux-parport-request@torque.net --
-- with the single word "unsubscribe" in the body of the message. --

This archive was generated by hypermail 2.0b3 on Wed 24 Nov 1999 - 11:26:09 EST