From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BC5A2C433F5 for ; Thu, 13 Jan 2022 20:30:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233071AbiAMUaM (ORCPT ); Thu, 13 Jan 2022 15:30:12 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33618 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231858AbiAMUaL (ORCPT ); Thu, 13 Jan 2022 15:30:11 -0500 Received: from metis.ext.pengutronix.de (metis.ext.pengutronix.de [IPv6:2001:67c:670:201:290:27ff:fe1d:cc33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 85E35C061574 for ; Thu, 13 Jan 2022 12:30:11 -0800 (PST) Received: from gallifrey.ext.pengutronix.de ([2001:67c:670:201:5054:ff:fe8d:eefb] helo=bjornoya.blackshift.org) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1n86jZ-0003lm-Vy; Thu, 13 Jan 2022 21:30:10 +0100 Received: from pengutronix.de (unknown [195.138.59.174]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) (Authenticated sender: mkl-all@blackshift.org) by smtp.blackshift.org (Postfix) with ESMTPSA id B752C180DC; Thu, 13 Jan 2022 20:30:08 +0000 (UTC) Date: Thu, 13 Jan 2022 21:30:04 +0100 From: Marc Kleine-Budde To: Srinivas Neeli Cc: Srinivas Goud , Naveen Kumar Gaddipati , Prasad Beer Prasad , linux-can Subject: Re: Queries on CAN frame work Message-ID: <20220113203004.jf2rqj2pirhgx72i@pengutronix.de> References: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="4xlilptybee4pkqi" Content-Disposition: inline In-Reply-To: X-SA-Exim-Connect-IP: 2001:67c:670:201:5054:ff:fe8d:eefb X-SA-Exim-Mail-From: mkl@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-can@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-can@vger.kernel.org --4xlilptybee4pkqi Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hello Srinivas Neeli, On 13.01.2022 18:14:06, Srinivas Neeli wrote: > This mail is regarding to understand more on CAN Frame work for CANFD > networks. let's discuss this on the CAN mailing list (Cc'ed). Feel free to subscribe (http://vger.kernel.org/vger-lists.html#linux-can). Please post non HTML mail. > Recently we did few experiments with our CANFD network. Stuff error > observed with different Nominal and Dataphase prescaler configuration > values, which we get from the frame work. >=20 >=20 > For lower baud rates separate prescalers are working good, but when we > switch to high baud rates(like 4Mbps and 5Mbps) observed the BUSOFF > state(Due to stuff errors) on IP(Xilinx). >=20 > With shared prescaler(low prescalers) we are not seeing the issue.. >=20 > In Iso spec also mentioned to avoid tolerance, we have to maintain > common TQ for Nominal and Data phase. >=20 > Spec: ISO 11898-1:2015(E) page no :50 >=20 > " If the same time quantum length is used in the nominal bit time and > in the data bit time and the positions of the sample points in the > nominal bit time are the same in all CAN nodes of a network, then > optimum clock tolerance is accomplished for networks using FD frames." >=20 > CIA: > https://can-newsletter.org/uploads/media/raw/f6a36d1461371a2f86ef0011a513= 712c.pdf >=20 > From above CAN-newsletter also suggested the same in recommendation 2 and= 3. >=20 > Recommendation 2: Set the BRPA bit-rate prescaler equal BRPB > Recommendation 3: Choose BRPA and BRPD as low as possible >=20 > Is there any possibility in framework to use shared prescalars for Nomina= l and Dataphase?. >=20 > One more question. How to calculate TDCO ?, is there any generic formula = for this ?. Marc --=20 Pengutronix e.K. | Marc Kleine-Budde | Embedded Linux | https://www.pengutronix.de | Vertretung West/Dortmund | Phone: +49-231-2826-924 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | --4xlilptybee4pkqi Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEK3kIWJt9yTYMP3ehqclaivrt76kFAmHgi8oACgkQqclaivrt 76lVngf+IEKFg5SXIPdJKnlfO4zPKaXm6xxtpfXLEMNg+b/idvJo3cbclQIbXqeT tcL7FPERg8qDbR7NpTgmpl1JlbKB6Kiul7LQLZ19sHmIbPCcGbA9RRKX8OLkRMWB hiIBq0l7GR4RYqTO1sGVE/jYnkRjag+LWYqZE3BAgmN9iFPATw3saFKXTbi7PEoS yv9x/G7EIBT3tJnID5yLPyVcYnHwQ31ug/Lg8rsvWHv/kFWp1I8ILVJXHao26aLN 2dpiBJX2UAkky9cVWjsPzf0WEh2GytzuZMv+O818dC2C+avfLJpIJdHXYr7psZcw EE7J8PecWYIJDFWQ0BwzQMYNcwodjw== =cwDM -----END PGP SIGNATURE----- --4xlilptybee4pkqi--