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 X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 04A8AC432BE for ; Mon, 16 Aug 2021 08:12:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E131361B00 for ; Mon, 16 Aug 2021 08:12:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234858AbhHPIMr (ORCPT ); Mon, 16 Aug 2021 04:12:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33596 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234824AbhHPIMq (ORCPT ); Mon, 16 Aug 2021 04:12:46 -0400 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 CC64FC061764 for ; Mon, 16 Aug 2021 01:12:14 -0700 (PDT) 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 1mFXj8-0003Xd-29; Mon, 16 Aug 2021 10:12:10 +0200 Received: from pengutronix.de (unknown [IPv6:2a02:810a:8940:aa0:3272:cc96:80a9:1a01]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-384) 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 3FA99668018; Mon, 16 Aug 2021 08:12:07 +0000 (UTC) Date: Mon, 16 Aug 2021 10:12:05 +0200 From: Marc Kleine-Budde To: Vincent Mailhol Cc: Stephen Hemminger , linux-can@vger.kernel.org, Stefan =?utf-8?B?TcOkdGpl?= , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v5 4/4] iplink_can: add new CAN FD bittiming parameters: Transmitter Delay Compensation (TDC) Message-ID: <20210816081205.7rjdskaui35f3jml@pengutronix.de> References: <20210814101728.75334-1-mailhol.vincent@wanadoo.fr> <20210814101728.75334-5-mailhol.vincent@wanadoo.fr> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="hiskfds7hw52oih6" Content-Disposition: inline In-Reply-To: <20210814101728.75334-5-mailhol.vincent@wanadoo.fr> 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-kernel@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --hiskfds7hw52oih6 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On 14.08.2021 19:17:28, Vincent Mailhol wrote: > At high bit rates, the propagation delay from the TX pin to the RX pin > of the transceiver causes measurement errors: the sample point on the > RX pin might occur on the previous bit. >=20 > This issue is addressed in ISO 11898-1 section 11.3.3 "Transmitter > delay compensation" (TDC). >=20 > This patch brings command line support to nine TDC parameters which > were recently added to the kernel's CAN netlink interface in order to > implement TDC: > - IFLA_CAN_TDC_TDCV_MIN: Transmitter Delay Compensation Value > minimum value > - IFLA_CAN_TDC_TDCV_MAX: Transmitter Delay Compensation Value > maximum value > - IFLA_CAN_TDC_TDCO_MIN: Transmitter Delay Compensation Offset > minimum value > - IFLA_CAN_TDC_TDCO_MAX: Transmitter Delay Compensation Offset > maximum value > - IFLA_CAN_TDC_TDCF_MIN: Transmitter Delay Compensation Filter > window minimum value > - IFLA_CAN_TDC_TDCF_MAX: Transmitter Delay Compensation Filter > window maximum value > - IFLA_CAN_TDC_TDCV: Transmitter Delay Compensation Value > - IFLA_CAN_TDC_TDCO: Transmitter Delay Compensation Offset > - IFLA_CAN_TDC_TDCF: Transmitter Delay Compensation Filter window >=20 > All those new parameters are nested together into the attribute > IFLA_CAN_TDC. >=20 > A tdc-mode parameter allow to specify how to operate. Valid options > are: >=20 > * auto: the transmitter automatically measures TDCV. As such, TDCV > values can not be manually provided. In this mode, the user must > specify TDCO and may also specify TDCF if supported. >=20 > * manual: Use the TDCV value provided by the user are used. In this ^^^^^ ^^^ singular plural > mode, the user must specify both TDCV and TDCO and may also > specify TDCF if supported. >=20 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 | --hiskfds7hw52oih6 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEK3kIWJt9yTYMP3ehqclaivrt76kFAmEaHdMACgkQqclaivrt 76kK2gf7ByQgT+oT/maYnG88lnvjMyyv+jPt7G6VOHxu8uc0KpNqzJbUstcfnFVg SXcJclJHbFeUj1PFtebuGRARQRTbCiYYC0YF9GcYdQoU7tFmeHEH0kiktmlKdiVu JbzcaEwnmmDBMFC8h6Cg1sOnnGpBcluLed1WEoqs/UmqYbY9U9owhzOV7NSbukQq TzlbpKPkXsAUZW2q2NBYvbljDubSC+Cb88C0Qxwa25ulQYkDmHnIqsq8HNSEYfsS hFVLndgSmtfobUKbDogLlqYN9vYN4bFl7nFeqcaH4ShlC01YefxjnEjBhJYRpXt5 8wpUiZ5+Jjxr7U3MpsgsQAbLQJClPA== =+mR+ -----END PGP SIGNATURE----- --hiskfds7hw52oih6--