From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Hello Bello" Subject: Re: serial port cannot be read in linux Date: Sat, 2 Jun 2007 23:40:49 +0200 Message-ID: <730b6c6b0706021440y7bb07837l104f1afbc25ee4fa@mail.gmail.com> References: <730b6c6b0706021439w41923cddvbf9fe953255190c0@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from ug-out-1314.google.com ([66.249.92.169]:64136 "EHLO ug-out-1314.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757724AbXFBVku (ORCPT ); Sat, 2 Jun 2007 17:40:50 -0400 Received: by ug-out-1314.google.com with SMTP id j3so466134ugf for ; Sat, 02 Jun 2007 14:40:49 -0700 (PDT) In-Reply-To: <730b6c6b0706021439w41923cddvbf9fe953255190c0@mail.gmail.com> Content-Disposition: inline Sender: linux-serial-owner@vger.kernel.org List-Id: linux-serial@vger.kernel.org To: linux-serial@vger.kernel.org Hello, I am trying to use a serial port in linux. My architecture is: -compaq evo n600c -debian GNU Linux 3.1 -vanilla kernel: Linux furge 2.6.21 #2 SMP Sat Jun 2 21:25:42 CEST 2007 i686 GNU/Linux This is my dmesg output: serial8250: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A serial8250: ttyS2 at I/O 0x3e8 (irq = 3) is a 16550A 00:02: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A I am trying to test the serial port by jumpering the receive and transmit pins of the serial port. Using this hardware, windows XP serial port tester program echos back the characters written to the port, so the hardware is ok. However, in Linux, the port stays dumb. I can write to it, but there is nothing to be read from it. e.g. cat /dev/ttyS0 > /tmp/serial.txt &; echo "a" > /dev/ttyS0; cat /tmp/serial.txt or cp /dev/ttyS0 /dev/tty1; echo "a" > /dev/ttyS0 I have read through the "Cannot write but not read" topic in this mailing list, but without any success. Also I have tried several serial port testing programs, all in vain. Kernel recompilations made no luck. I would really appreciate your help, Thanks, Gabor