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Date: Thu, 7 Nov 2002 16:41:55 -0800
To: jt@hpl.hp.com, Linux kernel mailing list <linux-kernel@vger.kernel.org>,
       Martin Diehl <lists@mdiehl.de>
Subject: Re: [Serial 2.5]: packet drop problem (FE ?)
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From: Jean Tourrilhes <jt@bougret.hpl.hp.com>
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On Fri, Nov 08, 2002 at 12:18:22AM +0000, Russell King wrote:
> On Thu, Nov 07, 2002 at 02:47:50PM -0800, Jean Tourrilhes wrote:
> > 	I tried swapping the IrDA dongles themselves, and this didn't
> > make any difference. No other device/driver is using irq4. I also try
> > using a FIR as a sender, and I still see this packet dropped in Rx in
> > 2.5.X. And this used to work properly way back when I had 2.4.X on
> > this box.
> > 	I'm kind of suspicious about the "fe" number above. Could
> > anybody tell me a bit more about what "fe" means ?
> 
> FE = framing error, which is an error which is solely detected by the
> hardware when the stop bit(s) are not the mark value.  They can appear
> when the wrong parity setting, number of stop bits, or baud rate is
> programmed.
> 
> If you were overruning the serial port FIFOs, then you would see "oe"
> errors.
> 
> What baud rate are you trying to run the link at?

	115k (max negociated speed).

	The IrDA layer report many CRC errors, that could be dropped
char or flipped bits. I see around one 2000B frame dropped every 10
frame, which would be one byte/bit every 20000B, which is roughly the
frequency of the FE in /proc.
	On the other hand, this number seems a bit low for a
configuration error.

	The serial port is configured via irattach like this :
-----------------------------------------
	tios->c_cflag     = CS8|CREAD|B9600|CLOCAL;
	
	/* Ignore break condition and parity errors */
 	tios->c_iflag     = IGNBRK | IGNPAR;
	tios->c_oflag     = 0;
	tios->c_lflag     = 0; /* set input mode (non-canonical, no echo,..) */
	tios->c_cc[VMIN]  = 1; /* num of chars to wait for, before delivery */
	tios->c_cc[VTIME] = 0; /* timeout before delivery */
-----------------------------------------
	Now, it's possible that somehow irattach did mess up this
bit.
	Is there a way to see the current flag configuration of the
port with setserial or /proc ?

> Russell King

	Thanks for your help...

	Jean
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