diff mbox series

[net-next,17/33] can: length: fix description of the RRS field

Message ID 20230621132914.412546-18-mkl@pengutronix.de (mailing list archive)
State Superseded
Delegated to: Netdev Maintainers
Headers show
Series [net-next,01/33] can: kvaser_usb: Add len8_dlc support | expand

Checks

Context Check Description
netdev/series_format warning Pull request is its own cover letter; Series longer than 15 patches
netdev/tree_selection success Clearly marked for net-next, async
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 9 this patch: 9
netdev/cc_maintainers fail 1 blamed authors not CCed: arunachalam.santhanam@in.bosch.com; 2 maintainers not CCed: wg@grandegger.com arunachalam.santhanam@in.bosch.com
netdev/build_clang success Errors and warnings before: 8 this patch: 8
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 9 this patch: 9
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 23 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Marc Kleine-Budde June 21, 2023, 1:28 p.m. UTC 
From: Vincent Mailhol <mailhol.vincent@wanadoo.fr>

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 macros.

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")
Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Reviewed-by: Thomas Kopp <Thomas.Kopp@microchip.com>
Link: https://lore.kernel.org/all/20230611025728.450837-3-mailhol.vincent@wanadoo.fr
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 include/linux/can/length.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
diff mbox series

Patch

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 <socketcan@hartkopp.net>
  * Copyright (C) 2020 Marc Kleine-Budde <kernel@pengutronix.de>
+ * Copyright (C) 2020 Vincent Mailhol <mailhol.vincent@wanadoo.fr>
  */
 
 #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