From patchwork Sat Aug 14 09:17:43 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vincent MAILHOL X-Patchwork-Id: 497618 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=-11.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT autolearn=unavailable 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 20695C432BE for ; Sat, 14 Aug 2021 09:19:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 03DAC60234 for ; Sat, 14 Aug 2021 09:19:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237660AbhHNJTj (ORCPT ); Sat, 14 Aug 2021 05:19:39 -0400 Received: from smtp03.smtpout.orange.fr ([80.12.242.125]:49608 "EHLO smtp.smtpout.orange.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237613AbhHNJTi (ORCPT ); Sat, 14 Aug 2021 05:19:38 -0400 Received: from tomoyo.flets-east.jp ([114.149.34.46]) by mwinf5d19 with ME id hMJz250060zjR6y03MK6ip; Sat, 14 Aug 2021 11:19:09 +0200 X-ME-Helo: tomoyo.flets-east.jp X-ME-Auth: bWFpbGhvbC52aW5jZW50QHdhbmFkb28uZnI= X-ME-Date: Sat, 14 Aug 2021 11:19:09 +0200 X-ME-IP: 114.149.34.46 From: Vincent Mailhol To: Marc Kleine-Budde , linux-can@vger.kernel.org Cc: =?utf-8?q?Stefan_M=C3=A4tje?= , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Vincent Mailhol Subject: [PATCH v4 0/7] add the netlink interface for CAN-FD Transmitter Delay Compensation (TDC) Date: Sat, 14 Aug 2021 18:17:43 +0900 Message-Id: <20210814091750.73931-1-mailhol.vincent@wanadoo.fr> X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org The main goal of this series is to add a netlink interface for the TDC parameters using netlink nested attributes. The series also contains a few fix on the current TDC implementation. This series completes the implementation of the Transmitter Delay Compensation (TDC) in the kernel which started in March with those two patches: - commit 289ea9e4ae59 ("can: add new CAN FD bittiming parameters: Transmitter Delay Compensation (TDC)") - commit c25cc7993243 ("can: bittiming: add calculation for CAN FD Transmitter Delay Compensation (TDC)") The netlink interface was missing from this series because the initial patch needed rework in order to make it more flexible for future changes. At that time, Marc suggested to take inspiration from the recently released ethtool-netlink interface. Ref: https://lore.kernel.org/linux-can/20210407081557.m3sotnepbgasarri@pengutronix.de/ ethtool uses nested attributes (c.f. NLA_NESTED type in validation policy). A bit of trivia: the NLA_NESTED type was introduced in version 2.6.15 of the kernel and thus actually predates Socket CAN. Ref: commit bfa83a9e03cf ("[NETLINK]: Type-safe netlink messages/attributes interface") Since then, Stephan shared additional remarks for improvement which are addressed in revision v4 of this series: Ref: https://lore.kernel.org/linux-can/75fa87a71a3f5fd7d7407a2c514b71690e56eb4e.camel@esd.eu/ The first patch allow a user to turn off a feature even if not supported (e.g. allow "ip link set can0 type can bitrate 500000 fd off" even if fd is not supported). This feature will be used later by the fifth patch of the series. The second patch allows TDCV and TDCO to be zero (previously, those values were assigned a special meaning). The third patch fixes the unit of the TDC parameters. In fact, those should be measured in clock period (a.k.a. minimum time quantum) and not in time quantum as it is done in current implementation. The fourth patch addresses the concern of Marc and Stefan concerning some devices which use a TDCO value relative to the Sample Point (so far, the TDC implementation used the formula SSP = TDCV + TDCO). To do so, an helper function to convert TDCO from an absolute value to a value relative to the sample point is added. The fifth patch is the real thing: the TDC netlink interface. The sixth patch allows to retrieve TDCV from the device through a callback function. The seventh and last patch does a bit of cleanup in the ES58x driver to remove some redundant TDC information from the documentation. ** Changelog ** v3 -> v4: - add a patch to the series to change the unit from time quantum to clock period (a.k.a. minimum time quantum). - add a callback function to retrieve TDCV from the device. v2 -> v3: - allows both TDCV and TDCO to be zero. - introduce the can_tdc_get_relative_tdco() helper function - other path of the series modified accordingly to above changes. RFC v1 -> v2: The v2 fixes several issue in can_tdc_get_size() and can_tdc_fill_info(). Namely: can_tdc_get_size() returned an incorrect size if TDC was not implemented and can_tdc_fill_info() did not include a fail path with nla_nest_cancel(). Vincent Mailhol (7): can: netlink: allow user to turn off unsupported features can: bittiming: allow TDC{V,O} to be zero and add can_tdc_const::tdc{v,o,f}_min can: bittiming: change unit of TDC parameters to clock periods can: dev: add can_tdc_get_relative_tdco() helper function can: netlink: add interface for CAN-FD Transmitter Delay Compensation (TDC) can: netlink: add can_priv::do_get_auto_tdcv() to retrieve tdcv from device can: etas_es58x: clean-up documentation of struct es58x_fd_tx_conf_msg drivers/net/can/dev/bittiming.c | 19 ++- drivers/net/can/dev/netlink.c | 192 +++++++++++++++++++++- drivers/net/can/usb/etas_es58x/es58x_fd.c | 7 +- drivers/net/can/usb/etas_es58x/es58x_fd.h | 23 +-- include/linux/can/bittiming.h | 80 ++++++--- include/linux/can/dev.h | 34 ++++ include/uapi/linux/can/netlink.h | 31 +++- 7 files changed, 332 insertions(+), 54 deletions(-)