From mboxrd@z Thu Jan 1 00:00:00 1970 From: Carl-Daniel Hailfinger Subject: Serial console UART confusion after machine S3 suspend and resume Date: Thu, 03 Feb 2005 18:16:10 +0100 Message-ID: <42025C5A.7070709@gmx.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Received: from pop.gmx.de ([213.165.64.20]:55447 "HELO mail.gmx.net") by vger.kernel.org with SMTP id S263205AbVBCRPn (ORCPT ); Thu, 3 Feb 2005 12:15:43 -0500 Sender: linux-serial-owner@vger.kernel.org List-Id: linux-serial@vger.kernel.org To: linux-serial@vger.kernel.org Hi, on resume from S3, my serial console prints garbage and stops working. If I disconnect the console while my machine is sleeping and reconnect immediately after, the serial console still prints garbage on resume but the follwowing command on my machine fixes the output for all subsequent kernel messages sent to the serial console. echo foo >/dev/ttyS0 Nothing besides outputting something to ttyS0 helps. Disconnecting and reconnecting, both logically and physically, doesn't have any positive effect. Could it be that the UART state is out-of-sync or something like that after resume and the serial console code doesn't notice, but the "normal" serial code notices and fixes things up? Are there any debugging options/patches/tips to find out what happens exactly? The machine works just fine after resume, so I could read dmesg for debugging output. Regards, Carl-Daniel -- http://www.hailfinger.org/