(Fwd) Linux-2.2-pre7/serial.c: DCD signal & 10 second interval

Ulrich Windl (ulrich.windl@rz.uni-regensburg.de)
Wed, 20 Jan 1999 16:32:15 +0100

(Brain-twister in CC:; retrying...)
------- Forwarded Message Follows -------
From: "Ulrich Windl" <ulrich.windl@rz.uni-regensburg.de>
Organization: Universitaet Regensburg, Klinikum
To: tytso@mit.edu
Date sent: Wed, 20 Jan 1999 16:24:14 +0100
Subject: Linux-2.2-pre7/serial.c: DCD signal & 10 second intervals
Copies to: linux-kernel@rutgers.vger.edu
Priority: normal

Hello Ted,

I have a strange problem with Linux (2.2-pre7): When I put pulses of
100 and 200ms on the DCD pin (in parallel to the RxD pin) of my
serial port (plain PC) every second, the receive code seems to
swallow rather exactly every 10th pulse (read character). I can
receive 9 characters without a problem though...

(Practically this makes my DCF77 receiver unusable. Unfortunately the
same hardware/program works fine with 2.0.36)

I have searched the code for that 10 second value, but couldn't find
it. Any ideas?

(With my PPS patches I have seen the opposite in 2.0 (and 2.1): Only
every 10th pulse gets through, but it seems to depend a lot on
timing. Most of the time the same code works. I have never found that
mysterious 10 second thing...)

Can that DCD monitoring be disabled?

Regards,
Ulrich Windl

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