Date: Fri, 26 Jan 2007 09:56:08 -0500
To: Paul Fulghum <paulkf@microgate.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Strange problem with tty layer
Message-ID: <20070126145608.GK7582@csclub.uwaterloo.ca>
References: <20070124204009.GA7584@csclub.uwaterloo.ca> <45B7CDB5.7020909@microgate.com> <20070125151639.GH7582@csclub.uwaterloo.ca> <20070126142041.GD7584@csclub.uwaterloo.ca> <45BA1556.8080808@microgate.com>
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From: lsorense@csclub.uwaterloo.ca (Lennart Sorensen)
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On Fri, Jan 26, 2007 at 08:51:02AM -0600, Paul Fulghum wrote:
> You can eliminate the tty buffering altogether
> by observing what gets passed to the line discipline.

I will have to find where in the code that is happening.

> I assume you are using the default line discipline N_TTY.
> 
> Look at what is passed to drivers/char/n_tty.c:n_tty_receive_buf()
> If all the data gets that far, then there is some issue
> with the line discipline or something further downstream.
> If not, then the problem is with the tty buffering (assuming
> you are correct that all data gets to the tty buffering code
> followed by a tty_flip_buffer_push call).

I am not sure actually.  I just open /dev/ttyn0 and /dev/ttyn1 and write
to one, and read from the other.  I didn't even know about the line
diciplines actually.  How do I tell which one I am using?

I have confirmed that all the data is being passed to
tty_insert_flip_string() in jsm_input().

--
Len Sorensen
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