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[124.33.176.97]) by smtp.gmail.com with ESMTPSA id e3-20020aa78c43000000b0063a04905379sm1703193pfd.137.2023.05.30.07.47.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 30 May 2023 07:47:37 -0700 (PDT) Sender: Vincent Mailhol From: Vincent Mailhol To: Marc Kleine-Budde , linux-can@vger.kernel.org, Thomas.Kopp@microchip.com Cc: Oliver Hartkopp , netdev@vger.kernel.org, marex@denx.de, Simon Horman , linux-kernel@vger.kernel.org, Vincent Mailhol Subject: [PATCH v3 2/3] can: length: fix description of the RRS field Date: Tue, 30 May 2023 23:46:36 +0900 Message-Id: <20230530144637.4746-3-mailhol.vincent@wanadoo.fr> X-Mailer: git-send-email 2.39.3 In-Reply-To: <20230530144637.4746-1-mailhol.vincent@wanadoo.fr> References: <20230507155506.3179711-1-mailhol.vincent@wanadoo.fr> <20230530144637.4746-1-mailhol.vincent@wanadoo.fr> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Spam-Status: No, score=-1.5 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_EF,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE, SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net The CAN-FD frames only have one reserved bit. The bit corresponding to Classical CAN frame's RTR bit is called the "Remote Request Substitution (RRS)" [1]. N.B. The RRS is not to be confused with the Substitute remote request (SRR). Fix the description in the CANFD_FRAME_OVERHEAD_SFF/EFF. The total remains unchanged, so this is just a documentation fix. In addition to the above add myself as copyright owner for 2020 (as coauthor of the initial version, c.f. Fixes tag). [1] ISO 11898-1:2015 paragraph 10.4.2.3 "Arbitration field": RSS bit [only in FD Frames] The RRS bit shall be transmitted in fD Frames at the position of the RTR bit in Classical Frames. The RRS bit shall be transmitted dominant, but receivers shall accept recessive and dominant RRS bits. Fixes: 85d99c3e2a13 ("can: length: can_skb_get_frame_len(): introduce function to get data length of frame in data link layer") Suggested-by: Thomas Kopp Signed-off-by: Vincent Mailhol --- include/linux/can/length.h | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/include/linux/can/length.h b/include/linux/can/length.h index b8c12c83bc51..521fdbce2d69 100644 --- a/include/linux/can/length.h +++ b/include/linux/can/length.h @@ -1,6 +1,7 @@ /* SPDX-License-Identifier: GPL-2.0 */ /* Copyright (C) 2020 Oliver Hartkopp * Copyright (C) 2020 Marc Kleine-Budde + * Copyright (C) 2020 Vincent Mailhol */ #ifndef _CAN_LENGTH_H @@ -64,7 +65,7 @@ * --------------------------------------------------------- * Start-of-frame 1 * Identifier 11 - * Reserved bit (r1) 1 + * Remote Request Substitution (RRS) 1 * Identifier extension bit (IDE) 1 * Flexible data rate format (FDF) 1 * Reserved bit (r0) 1 @@ -95,7 +96,7 @@ * Substitute remote request (SRR) 1 * Identifier extension bit (IDE) 1 * Identifier B 18 - * Reserved bit (r1) 1 + * Remote Request Substitution (RRS) 1 * Flexible data rate format (FDF) 1 * Reserved bit (r0) 1 * Bit Rate Switch (BRS) 1