[OT - MPC5200B] strange framing, break problems with uart

Albrecht Dreß albrecht.dress at arcor.de
Fri Feb 4 05:34:32 EST 2011

Hi all,

sorry for a slightly off-topic question, but I hope someone here on the list may be able to help me...

I have a strange problem with the psc uart of the mpc5200b, running (still), with my baud rate divisor selection patch [1].

The uart runs at 115.2 kBaud with rtc/cts handshake to send bigger chunks of data to the '5200.  I noticed "missing" data in the input stream, and inspected the uart status using the TIOCGICOUNT ioctl which tells me that a bunch of framing and break errors occurred.  I "tapped" the RxD line and connected it via a level shifter to a standard 16450-style uart in a (much faster) Linux PC, and *that* one receives the *complete* stream *without any* break or framing errors!

I also looked at the waveforms with an oscilloscope, and they look pretty fine.  The port configuration should also be ok, re-checked with a bdi3000 jtag debugger - it's PSC3, set to '1100', with PSC3_0 .. PSC3_3 being used here.

This leads me to the assumption that either the hardware handshake or the Linux driver or both are broken...  any insight would be highly appreciated!


[1] <http://patchwork.ozlabs.org/patch/48884/>; included in 2.6.37
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