ISO 11898-1 Chapter 8.4.2.3 defines a 4 bit data length code (DLC) table which
maps the DLC to the payload length of the CAN frame in bytes:
DLC -> payload length
0 .. 8 -> 0 .. 8
9 .. 15 -> 8
Although the DLC values 8 .. 15 in Classical CAN always result in a payload
length of 8 bytes these DLC values are transparently transmitted on the CAN
bus. As the struct can_frame only provides a 'len' element (formerly 'can_dlc')
which contains the plain payload length ( 0 .. 8 ) of the CAN frame, the raw
DLC is not visible to the application programmer, e.g. for testing use-cases.
To access the raw DLC values 9 .. 15 the len8_dlc element is introduced, which
is only valid when the payload length 'len' is 8 and the DLC is greater than 8.
The len8_dlc element is filled by the CAN interface driver and used for CAN
frame creation by the CAN driver when the CAN_CTRLMODE_CC_LEN8_DLC flag is
supported by the driver and enabled via netlink configuration interface.
Reported-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
This patch fixes paths mentioned in the files which are wrong now, due the move
of the files in the previous patch.
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
This makes it possible to import header from the kernel more easily, e.g.:
cd $path_to_linux_repo
make headers_install
rsync -a --exclude .\* usr/include/linux/can* $path_to_can_utils/include/linux
[mkl: also move isotp.h although Uwe skipped it as it is not
part of the upstream kernel; adapt commit log accordingly]
Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Oliver Hartkopp
Yegor Yefremov
Marc Kleine-Budde
Uwe Kleine-König