From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wolfgang Grandegger Subject: Re: [PATCH] flexcan: disable bus error interrupts for the i.MX28 Date: Mon, 08 Oct 2012 11:03:46 +0200 Message-ID: <507296F2.9010402@grandegger.com> References: <5065A35B.3020702@grandegger.com> <20121007030858.GJ20231@S2101-09.ap.freescale.net> <50719647.4070404@grandegger.com> <7FE21149F4667147B645348EC60578850B2A361F@039-SN2MPN1-011.039d.mgd.msft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from ngcobalt02.manitu.net ([217.11.48.102]:41329 "EHLO ngcobalt02.manitu.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750733Ab2JHJDx (ORCPT ); Mon, 8 Oct 2012 05:03:53 -0400 In-Reply-To: <7FE21149F4667147B645348EC60578850B2A361F@039-SN2MPN1-011.039d.mgd.msft.net> Sender: linux-can-owner@vger.kernel.org List-ID: To: Dong Aisheng-B29396 Cc: Shawn Guo , Linux Netdev List , Linux-CAN , Hui Wang Hi Dong, On 10/08/2012 09:59 AM, Dong Aisheng-B29396 wrote: > Hi Wolfgang, > >> On 10/07/2012 05:09 AM, Shawn Guo wrote: >>> On Fri, Sep 28, 2012 at 03:17:15PM +0200, Wolfgang Grandegger wrote: >>>> Due to a bug in most Flexcan cores, the bus error interrupt needs to >>>> be enabled. Otherwise we don't get any error warning or passive >>>> interrupts. This is _not_ necessay for the i.MX28 and this patch >>>> disables bus error interrupts if "berr-reporting" is not requested. >>>> This avoids bus error flooding, which might harm, especially on >>>> low-end systems. >>>> >>>> To handle such quirks of the Flexcan cores, a hardware feature flag >>>> has been introduced, also replacing the "hw_ver" variable. So far >>>> nobody could tell what Flexcan core version is available on what >>>> Freescale SOC, apart from the i.MX6Q and P1010, and which bugs or >>>> features are present on the various "hw_rev". >>>> >>>> CC: Hui Wang >>>> CC: Shawn Guo >>>> Signed-off-by: Wolfgang Grandegger >>>> --- >>>> >>>> Concerning the bug, I know that the i.MX35 does have it. Maybe other >>>> Flexcan cores than on the i.MX28 does *not* have it either. If you >>>> have a chance, please check on the P1010, i.MX6Q, i.MX51, i.MX53, >>>> etc. >>> >>> >From what I can tell, i.MX35, i.MX51 and i.MX53 use the same version, >>> so they should all have the bug. And for i.MX6Q, since it uses a >>> newer version even than i.MX28, I would believe it's affected by the bug. >>> But I'm copying Dong who should have better knowledge about this to >>> confirm. >> >> Thank for clarification. I have a i.MX6Q board but without CAN adapter :(, >> unfortunately. Otherwise I would try it out myself. >> > How did you verify this issue? I provoke state changes, e.g. by sending a message without connection to the bus. On the Mx28, the TWRN_INT/RWRN_INT/(BOFF_INT?) does trigger the corresponding interrupt. This does not work properly on some other cores, e.g. the Mx35. Therefore we enable ERR_INT for those cores to realize state changes. > I just checked our ic guy of flexcan, it seems he also had no sense of this issue. > > Below is some version info what I got: > Mx6s use FlexCAN3, with IP version 10.00.12.00 > Mx53 use FlexCAN2 (with glitch filter), with IP version 03.00.00.00 > Mx28 use FlexCAN2 (with glitch filter), with IP version 03.00.04.00 > Mx35 use FlexCAN2 (without glitch filter) , with IP version 03.00.00.00 > Mx25 use FlexCAN2 (without glitch filter), with IP version 03.00.00.00 > I'm not sure if mx6q has such issue. OK, we need to find that out experimentally. Wolfgang.