From mboxrd@z Thu Jan 1 00:00:00 1970 From: Viktor Babrian Subject: c_can: (newbie) high system load when frame not acked? Date: Mon, 12 Jan 2015 18:18:26 +0100 Message-ID: References: <9c72f211-becc-4c0f-94f6-0700dfb1195e@GRBSR0089.marel.net> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; format=flowed; charset=US-ASCII Return-path: Received: from plane.gmane.org ([80.91.229.3]:55738 "EHLO plane.gmane.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750882AbbALRZG (ORCPT ); Mon, 12 Jan 2015 12:25:06 -0500 Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1YAijf-00031K-Jo for linux-can@vger.kernel.org; Mon, 12 Jan 2015 18:25:03 +0100 Received: from login.renyi.hu ([193.224.79.10]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Mon, 12 Jan 2015 18:25:03 +0100 Received: from v by login.renyi.hu with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Mon, 12 Jan 2015 18:25:03 +0100 In-Reply-To: <9c72f211-becc-4c0f-94f6-0700dfb1195e@GRBSR0089.marel.net> Sender: linux-can-owner@vger.kernel.org List-ID: To: linux-can@vger.kernel.org Hi, I am new to linux with can though I have had some experience with both separately. I have here an am3359 board (having DCAN CAN controller). CAN transciever is terminated by a 60R resistor, no other party connected (no cables etc). I set up a can transmission using cansend: # ip link set can1 type can bitrate 500000 triple-sampling on # ip link set can1 up # cansend can1 5A1#11.2233.44556677.88 Oscilloscope probe is on canh. Everything works just fine, except: - Frame is retransmitted for ever (seen on bus) - user experience drops (serial terminal hardly echoes) - load is up - top shows sirq level of 75-80% after bringing down can1 with # ip link set can1 down, I see that load is fine again (=0), however frame retransmission is going on still (observed by oscilloscope). Transmission stops only after enabling can1 again: # ip link set can1 up Is this expected? Has anybody seen similar behavior? I am using linux kernel 3.14.26. I have also tried c_can driver from 3.19rc3 ("backported"=copied), same results. Thanks in advance, Viktor babrian